JPWO2017187942A1 - Inkjet recording method - Google Patents

Abstract

Ink composition A including at least a microcapsule encapsulating a polymerizable compound, a high boiling point solvent, water, and a colorant, and an ink including a microcapsule encapsulating at least a polymerizable compound, a high boiling point solvent, water, and carbon black And a step of discharging the composition B onto the substrate, and a step of heating the ink composition A and the ink composition B discharged onto the substrate, and the absorbance ABSA and the ink composition of the ink composition A The absorbance ABSB of the product B satisfies the formula (1), and the concentration MA of the high boiling point solvent contained in the ink composition A and the concentration MB of the high boiling point solvent contained in the ink composition B satisfy the formula (2). Inkjet recording method to satisfy. ABSA <ABSB formula (1) MA <MB formula (2)

Description

  The present invention relates to an ink jet recording method.

  As a recording method for recording an image on a substrate, there are an electrophotographic method, a sublimation type thermal transfer method, a melt type thermal transfer method, an ink jet method and the like. The ink jet recording method is advantageous in that it can be carried out with an inexpensive apparatus and the running cost is low because the ink can be used efficiently.

  As one of the ink jet recording methods, there is an ink jet recording method using an ink jet ink that can be cured by irradiation with an active energy ray such as ultraviolet rays after the ink discharged to the substrate is irradiated with infrared rays and heated.

  As an inkjet recording method, for example, an inkjet ink containing water, a photopolymerization initiator, and a capsule whose core is covered with a polymer shell, the capsule shell has a cross-linked structure, and the core Ejecting inkjet ink containing at least one chemically reactive compound that forms a reaction product upon irradiation with ultraviolet rays, heating step of irradiating infrared rays to the inkjet ink ejected onto the substrate, and irradiating with ultraviolet rays (UV) Ink jet recording methods having a step of curing are proposed (for example, see International Publication No. 2015/158748).

  In addition, as another inkjet recording method, a step of applying to a recording medium an ink containing a pigment, resin fine particles, and a water-soluble high-boiling volatile solvent; An image recording method having a heating step has been proposed (see, for example, JP-A-2014-34113).

Aqueous ink compositions that can be cured by irradiation with active energy rays have different absorbances at wavelengths of 800 nm to 1400 nm depending on the color and color of the colorant contained in the ink composition. The evaporation rate of water in the ink composition differs in the heating step performed before the step.
When monochromatic ink is used as in International Publication No. 2015/158748, the interaction between colors does not affect the image, but two or more ink compositions having different water evaporation rates are the same. When applied on the material and heated, one ink composition may be fixed to the substrate first, and the other ink composition may be fixed later. In particular, when a water-based ink composition containing capsules as described in International Publication No. 2015/158748 is used in combination of two or more colors, the evaporation rate of water in the ink composition varies depending on the hue of the ink composition. Cheap. When the ink composition is fixed on the substrate, the ink composition to be fixed later tends to easily change the shape of the liquid droplets and to cause color bleeding. The color bleed refers to a phenomenon in which a desired color cannot be obtained because two adjacent ink compositions are mixed.
Also, a water-based ink composition containing capsules as described in International Publication No. 2015/158748 is a case where an ink composition of two or more colors is used, and in particular, carbon black that absorbs heat and easily generates heat is used. When the black ink contained and the ink of another color are used in combination, the temperature of the ink composition becomes too high due to heating, and the microcapsules may be destroyed. When the microcapsules contained in the ink composition are broken, the amount of microcapsules that can contribute to the immobilization of the ink composition is reduced, so that the ink composition is hardly immobilized on the substrate. Since the ink composition containing the destroyed microcapsules is more likely to change the shape of the droplets on the substrate than the ink composition containing the undestructed microcapsules, the black ink and the inks of other colors Is applied to the same substrate, the black ink droplets tend to spread and color bleeding tends to occur.

  On the other hand, as a method for recording an image by heating an ink composition, for example, an image recording method described in JP-A-2014-34113 is known. In the image recording method described in Japanese Patent Application Laid-Open No. 2014-34113, the resin fine particles contained in the ink are heated to a temperature equal to or higher than the minimum film-forming temperature, and an image is recorded. When this method is used for an ink composition containing microcapsules, the temperature of the ink composition becomes too high due to heating, and the microcapsules may be destroyed. The ink composition containing the destroyed microcapsules contains carbon black that easily absorbs heat and generates heat because the shape of the droplet is likely to change on the substrate as compared with the ink composition containing undestructed microcapsules. When black ink and other color inks are applied on the same substrate, the droplets of black ink tend to spread and color bleeding tends to occur.

  In view of the above circumstances, in one embodiment of the present invention, when a multicolor image is recorded using a plurality of water-based ink compositions, an ink jet recording method in which the occurrence of color bleeding in the image is suppressed. Is provided.

Embodiments of the present invention include the following aspects.
<1> Ink composition A containing at least a polymerizable compound, a microcapsule containing a high boiling point solvent, water, and a colorant, and a microcapsule containing at least a polymerizable compound, a high boiling point solvent, water, and carbon black An ink composition B containing the ink composition B, and a heating step of heating the ink composition A and the ink composition B ejected onto the substrate, and the absorbance ABS of the ink composition A The absorbance ABS _{B of A} and the ink composition B satisfies the following formula (1), and the concentration M _A of the high-boiling solvent contained in the ink composition _A and the concentration M of the high-boiling solvent contained in the ink composition B _An ink jet recording method in which _B satisfies the following formula (2).

ABS _A <ABS _B type (1)
M _A <M _B (2)

In formula (1), ABS _A and ABS _B represent the average values of the absorbances of the ink composition A and the ink composition B at wavelengths of 800 nm to 1400 nm, respectively.
In the formula (2), M _A or M _B represents a concentration on the mass basis of the high boiling point solvent contained in the ink composition A or the ink composition B with respect to the total mass of each ink composition.

<2> The inkjet recording method according to <1>, wherein the heating step is performed by irradiating the ink composition A and the ink composition B with infrared rays.
_{<3> ABS A, ABS B} , M A, and _{M B-jet} recording method according to <1> or <2> satisfying the following equation (3).

_{{1 + 0.01 × (ABS B} / ABS A)} × M A <M B <{1 + 0.04 × (ABS B / ABS A)} × M A formula (3)

_{<4> ABS A, ABS B} , M A, and _{M B-jet} recording method according to any one of satisfying the following formula (4) <1> to <3>.

_{{1 + 0.015 × (ABS B} / ABS A)} × M A <M B <{1 + 0.03 × (ABS B / ABS A)} × M A (4)

<5> _{M A} is not more than 12 wt% 5 wt% or more based on the total weight of the ink composition A, _{M B} is 15 wt% or less 7 mass% or more with respect to the total mass of the ink composition B The inkjet recording method according to any one of <1> to <4>.
<6> The inkjet recording method according to any one of <1> to <5>, wherein the heating step heats the ink composition A and the ink composition B under the same conditions.

<7> The ink composition A contains 4.0% by mass to 6.0% by mass of a quinacridone pigment as a colorant with respect to the total mass of the ink composition A, and the ink composition B is an ink composition B. The inkjet recording method according to any one of <1> to <6>, comprising 1.5% by mass to 2.5% by mass of carbon black with respect to the total mass of the ink.
<8> The ink composition A contains 1.7% by mass to 3.1% by mass of a copper phthalocyanine pigment as a colorant with respect to the total mass of the ink composition A, and the ink composition B is an ink composition. The inkjet recording method according to any one of <1> to <6>, comprising 1.5% by mass to 2.5% by mass of carbon black with respect to the total mass of B.
<9> The ink composition A contains 3.0% by mass to 4.4% by mass of a monoazo pigment as a colorant with respect to the total mass of the ink composition A, and the ink composition B is an ink composition B. The inkjet recording method according to any one of <1> to <6>, comprising 1.5% by mass to 2.5% by mass of carbon black with respect to the total mass of the ink.
<10> The high boiling point solvent contained in the ink composition A and the ink composition B is a water-soluble solvent having a boiling point of 180 ° C. or higher and 280 ° C. or lower, and any one of <1> to <9>. Inkjet recording method.
<11> The inkjet recording method according to any one of <1> to <10>, wherein each of the microcapsules contained in the ink composition A and the ink composition B further includes a photopolymerization initiator.
<12> The inkjet recording method according to any one of <1> to <11>, further including an irradiation step of irradiating the ink composition A and the ink composition B heated by the heating step.

<13> Ink composition A includes at least a microcapsule encapsulating a polymerizable compound, a high-boiling solvent, water, and a microcapsule encapsulating at least a polymerizable compound, and a high-boiling solvent containing water and a copper phthalocyanine pigment. , Water, and an ink composition A2 containing a quinacridone pigment, and an ink composition A3 containing a microcapsule containing at least a polymerizable compound, a high boiling point solvent, water, and a monoazo pigment. The composition A1, the ink composition A2, the ink composition A3, and the ink composition B are ejected onto the base material, and the heating step is performed on the ink composition A1, the ink composition A2, and the ink composition ejected onto the base material. A3 and the ink composition B are heated, and the absorbance ABS _{A1 of} the ink composition _A1 and the absorbance ABS _A2 of the ink composition _A2 Absorbance _{ABS A3} of the ink composition A3, and the absorbance ABS _B of the ink composition B, the following equation (5), satisfy the equation (6) and (7), the high boiling point solvent contained in the ink composition A1 The concentration M _A1 , the concentration M _{A2 of} the high boiling point solvent contained in the ink composition _A2 , the concentration M _{A3 of} the high boiling point solvent contained in the ink composition _A3 , and the concentration M _{B of the} high boiling point solvent contained in the ink composition B are as follows: The inkjet recording method according to any one of <1> to <12>, which satisfies the following formula (8), formula (9), and formula (10):

ABS _A1 <ABS _B type (5)
ABS _A2 <ABS type _B (6)
ABS _A3 <ABS type _B (7)
M _A1 <M _B (8)
M _A2 <M _B (9)
M _A3 <M _B (10)

In the formulas (5), (6), and (7), ABS _A1 , ABS _A2 , ABS _A3 , and ABS _B are the ink composition A1, the ink composition A2, the ink composition A3, and the ink composition. The average value of the absorbance of each of B at wavelengths of 800 nm to 1400 nm is represented.
Equation (8), equation (9), and wherein _(10), M _A1, M _{A2, M A3,} or _{M B,} the ink composition A1, the ink composition A2, the ink composition A3, or the ink composition The high-boiling point solvent contained in B represents the concentration based on mass relative to the total mass of each ink composition.

  According to one embodiment of the present invention, there is provided an ink jet recording method in which the occurrence of color bleeding in an image is suppressed when a multicolor image is recorded using a plurality of types of aqueous ink compositions.

FIG. 1 is a diagram illustrating an image of an evaluation sample in the example. FIG. 2 is a diagram illustrating an image for evaluating dischargeability in the embodiment. FIG. 3 is a diagram illustrating an image of a four-color evaluation sample in the example. FIG. 4 is a diagram illustrating an image for evaluating the dischargeability of four colors in the example.

  Hereinafter, specific embodiments of the present disclosure will be described in detail. However, the present disclosure is not limited to the following embodiments, and may be implemented with appropriate modifications within the scope of the object of the present disclosure. can do.

In the present specification, numerical ranges indicated using “to” indicate ranges including the numerical values described before and after “to” as the minimum value and the maximum value, respectively.
In the numerical ranges described stepwise in the present specification, the upper limit value or lower limit value described in a numerical range may be replaced with the upper limit value or lower limit value of the numerical range described in other steps. . Further, in the numerical ranges described in this specification, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the values shown in the examples.
In this specification, the amount of each component in the composition is the total amount of the plurality of substances present in the composition unless there is a specific indication when there are a plurality of substances corresponding to each component in the composition. Means.

  In this specification, the term “process” is not limited to an independent process, and is included in this term if the intended purpose of the process is achieved even when it cannot be clearly distinguished from other processes. It is.

In this specification, “light” is a concept including active energy rays such as γ rays, β rays, electron beams, ultraviolet rays, and visible rays.
In this specification, ultraviolet rays may be referred to as “UV (Ultra Violet) light”.
In this specification, infrared rays are sometimes referred to as “IR (infrared) light”.
In this specification, light generated from an LED (Light Emitting Diode) light source may be referred to as “LED light”.
In the present specification, “(meth) acrylic acid” is a concept including both acrylic acid and methacrylic acid, “(meth) acrylate” is a concept including both acrylate and methacrylate, and “( The term “(meth) acryloyl group” is a concept including both an acryloyl group and a methacryloyl group.

≪Inkjet recording method≫
Ink jet recording method includes at least a microcapsule enclosing a polymerizable compound, a high boiling point solvent, water, and an ink composition A containing a colorant, and a microcapsule enclosing at least a polymerizable compound, a high boiling point solvent, water, and A discharge step of discharging the ink composition B containing carbon black onto the substrate, and a heating step of heating the ink composition A and the ink composition B discharged onto the substrate. absorbance ABS _B absorbance ABS _a and ink composition B may satisfy the following formula (1), and the high boiling point solvent contained in the concentration M _a and ink composition B of the high-boiling solvent contained in the ink composition a concentration _{M B} satisfies the following equation (2).
ABS _A <ABS _B type (1)
M _A <M _B (2)

In formula (1), ABS _A and ABS _B represent the average values of the absorbances of the ink composition A and the ink composition B at wavelengths of 800 nm to 1400 nm, respectively.
In the formula (2), M _A or M _B represents a concentration on the mass basis of the high boiling point solvent contained in the ink composition A or the ink composition B with respect to the total mass of each ink composition.

Details of the mechanism of action in the present disclosure are unknown, but are assumed as follows.
The water-based ink composition that can be cured by irradiation with active energy rays has different absorbances at wavelengths of 800 nm to 1400 nm depending on the color and type of the colorant contained in the ink composition. In the heating process performed before the process, the evaporation rate of water in the ink may be different. In particular, when a water-based ink composition containing capsules as described in International Publication No. 2015/158748 is used in combination of two or more colors, the evaporation rate of water in the ink composition varies depending on the hue of the ink composition. Cheap. When two or more ink compositions with different water evaporation rates are applied on the same substrate and heated, one ink composition is first fixed to the substrate and the other ink composition is fixed later. Therefore, color bleed easily occurs when a multicolor image is recorded. In addition, when an aqueous ink composition containing a capsule as described in International Publication No. 2015/158748 is used in combination of two or more colors, the black ink containing carbon black that easily absorbs heat and generates heat. If the ink is a combination of inks of other colors, the black ink droplets are likely to spread and color bleeding is likely to occur.
The ink described in JP-A-2014-34113 forms a film by heating resin fine particles and records an image. However, if a similar method is used in an ink composition containing microcapsules, the microcapsules are destroyed, and the ink It becomes difficult for the composition to be immobilized on the substrate. This destruction of microcapsules due to heating is particularly likely to occur in black ink containing carbon black that absorbs heat and easily generates heat. Therefore, when black ink and other color inks are applied on the same substrate, the droplets of black ink are likely to spread and color bleeding is likely to occur.
The inkjet recording method of the present disclosure is based on an ink composition A containing microcapsules, a high boiling point solvent, water, and a colorant, and an ink composition B containing microcapsules, a high boiling point solvent, water, and carbon black. It heats after discharging to a material. As a result, the water contained in the ink composition A and the ink composition B evaporates, and the concentration of the high boiling point solvent increases, so that both the ink composition A and the ink composition B have a low zeta potential and the surface charge. The charge repulsion of the microcapsules dispersed by the repulsion becomes weak and the microcapsules aggregate. As a result, since the ink composition A and the ink composition B are thickened, the ink composition A and the ink composition B are fixed to the substrate.
At this time, the absorbance of the ink composition A and the ink composition B and the concentration of the high boiling point solvent satisfy the above formulas (1) and (2), so that the microcapsules containing carbon black are destroyed by heating. In the ink composition B that tends to occur, the microcapsules can be aggregated before the microcapsules are destroyed. Therefore, the ink composition B can be fixed while suppressing the change in the shape of the droplets on the base material of the ink composition B. As a result, the inkjet recording method of the present disclosure is considered to record an image in which the occurrence of color bleeding is suppressed.

<Discharge process>
Ink jet recording method includes at least a microcapsule enclosing a polymerizable compound, a high boiling point solvent, water, and an ink composition A containing a colorant, and a microcapsule enclosing at least a polymerizable compound, a high boiling point solvent, water, and A discharge step of discharging the ink composition B containing carbon black onto a substrate;
Note that the high boiling point solvent, water, and the colorant may be included in the microcapsule or may be included in the ink composition without being included in the microcapsule. Further, when the ink composition further contains a sensitizer or other additive, the sensitizer or other component may be included in the microcapsule, and is not included in the microcapsule but included in the ink composition. It may be.
In the ink jet recording method, a desired image can be formed on a substrate by ejecting the ink composition A and the ink composition B onto the substrate.
Between the ink composition A and the ink composition B used in the inkjet recording method of the present disclosure, the absorbance and the concentration of the high-boiling solvent satisfy the relationship between the formulas (1) and (2).

Ink composition A and ink composition B is absorbance meet ABS _A and the absorbance ABS _B Togashiki (1), by satisfying the high boiling solvent the concentration _{M A} and the density _{M B} Togashiki (2), the ink composition In the product A and the ink composition B, the ink composition can be immobilized on the substrate while suppressing the destruction of the microcapsules due to heating. In particular, in the ink composition B, the microcapsules can be aggregated before the microcapsules are destroyed by heating. As a result, color bleeding can be suppressed.

The absorbance ABS _A of the ink composition _A and the absorbance ABS _B of the ink composition B satisfy the following formula (1).
ABS _A <ABS _B type (1)
In formula (1), ABS _A and ABS _B represent the average values of the absorbances of the ink composition A and the ink composition B at wavelengths of 800 nm to 1400 nm, respectively.

The absorbance at a wavelength of 800 nm to 1400 nm can be measured by the following method.
Prepare a diluted solution obtained by diluting the ink composition to be measured 1000 times by mass with ultrapure water, put the diluted solution in a quartz cell having an optical path length of 0.2 mm, and put ultrapure water in a control cell to perform measurement. . The measurement is performed under the following conditions using a spectrophotometer (for example, V-7200 of JASCO Corporation).
-Condition-
Measurement wavelength: 800 nm to 1400 nm
Measurement interval: every 1 nm

  The average value of the absorbance measured at the wavelength of 800 nm to 1400 nm is calculated using the following mathematical formula (A).

And the absorbance ABS _B absorbance ABS _A and ink composition B of the ink composition A, satisfying the equation (1) (i.e., toward the ink composition A is smaller absorbance than the ink composition B), the ink When the same amount of infrared rays (light with a wavelength of 800 nm to 1400 nm) is incident on the composition A and the ink composition B, the ink composition A is less likely to increase the temperature of the composition, and the ink composition B is more It shows that the temperature of the composition tends to rise.
In the ink composition A and the ink composition B in the present disclosure, the absorbance value generally depends on the type and content of the colorant or carbon black contained in the ink composition.

Concentration M _B of the high-boiling solvent contained in the concentration M _A and ink composition B of the high-boiling solvent contained in the ink composition A, satisfies the following formula (2).
M _A <M _B (2)
In the formula (2), M _A or M _B represents a concentration on the mass basis of the high boiling point solvent contained in the ink composition A or the ink composition B with respect to the total mass of each ink composition.

When M _A or M _B satisfies the formula (2), when the ink composition A and the ink composition B are heated, the zeta potential of the ink composition is higher in the ink composition B than in the ink composition A. Tends to be low, and the microcapsules tend to aggregate. As a result, since the microcapsules can be aggregated before the destruction of the microcapsules in the ink composition B, color bleeding can be suppressed.

M _A in the ink composition A is preferably at most 30 mass% or more 1% by weight relative to the total weight of the ink composition A. When M _A is 1% by mass or more, improved ejection of the ink composition A, image color bleed is further suppressed can be obtained. On the other hand, if M _A is 30 wt% or less, the ink composition A more excellent film strength, an image having excellent graininess obtained. The same applies to M _B in the ink composition B.

  In this specification, the graininess means the state of spreading of the ink composition droplets in the formed image, and “excellent graininess” means that the ink composition droplets in the image are desired. In this state, the color of the base material is difficult to see and the image is not missing.

M _A of ink composition A, film strength, discharge properties, color bleeding, and in view of graininess, 20 wt% preferably less than 1% by weight relative to the total weight of the ink composition A, 3 wt% or more 18 mass% or less is more preferable, and 5 mass% or more and 12 mass% or less are still more preferable.
M _B of the ink composition B is preferably 3 mass% to 25 mass% relative to the total weight of the ink composition B from the same viewpoint as above, more preferably 20 mass% to 5 mass%, 7 mass % To 15% by mass is more preferable, and 9% to 16% by mass is particularly preferable.

As a combination of M _A and M _B , M _A is 5% by mass or more and 12% by mass or less with respect to the total mass of the ink composition A, and M _B is based on the total mass of the ink composition B. It is preferable that they are 7 mass% or more and 15 mass% or less.
When M _A and M _B are in the above combination, an image formed with the ink composition A and the ink composition B is excellent in graininess, and color bleeding is further suppressed.

  The ink composition A and the ink composition B include water, a high-boiling solvent, and microcapsules. Since water evaporates through the heating process and the concentration of the high-boiling solvent in the ink composition increases, The capsules agglomerate and the ink composition is fixed to the substrate. That is, as the concentration of the high boiling point solvent in the ink composition A and the ink composition B is higher, the microcapsules are more easily aggregated and the immobilization of the ink composition is more likely to proceed.

_ABS A in the ink composition A and ink composition B, _ABS B, _{M A,} and _{M B} preferably satisfies the following formula (3).
_{(1 + 0.01 × (ABS B} / ABS A)) × M A <M B <(1 + 0.04 × (ABS B / ABS A)) × M A formula (3)

Equation (3) is a preferred expression of the concentration of the high boiling point solvent were expressed with _{M A} and _{M B} in the ink composition B having the ink composition A and absorbance ABS _B has an absorbance ABS _A, is _{M B} If it exceeds (1 + 0.01 × (ABS _B / ABS _A )) × M _A , color bleeding is further suppressed. On the other hand, the _{M B (1 + 0.04 × (} ABS B / ABS A)) is less than × _{M A,} graininess is improved. In addition, the wear resistance of the formed image is improved.
The coefficients indicated by “0.01” and “0.04” are values empirically obtained through experiments.

From the same viewpoint as above, the ink composition A and ink composition _B, ABS A, _ABS B, _{M A,} and _{M B} is more preferably satisfies the following formula (4). Formula (4) is a formula that expresses a particularly preferable high-boiling-point solvent concentration in the ink composition A having the absorbance ABS _A and the ink composition _B having the absorbance ABS _B using M _A and M _{B.
(1 + 0.015 × (ABS B} / ABS A)) × M A <M B <(1 + 0.03 × (ABS B / ABS A)) × M A (4)

The coefficients indicated by “0.015” and “0.03” are values empirically obtained through experiments.
When Expression (4) is satisfied, Expression (3) and Expression (2) are also satisfied. When Expression (3) is satisfied, Expression (2) is also satisfied.

  Hereinafter, each component contained in the ink composition A and the ink composition B will be described in detail. The ink composition A and the ink composition B are also collectively referred to as “ink composition”.

[Ink composition]
The ink composition A includes at least microcapsules enclosing a polymerizable compound, a high boiling point solvent, water, and a colorant.
The ink composition B includes at least microcapsules encapsulating a polymerizable compound, a high boiling point solvent, water, and carbon black.
Ink composition A and ink composition B satisfy the above formulas (1) and (2).
The components commonly contained in the ink composition A and the ink composition B may be the same or different, and may include other components such as a sensitizer in addition to the above components. Good.
In the inkjet recording method of the present disclosure, two types of ink compositions may be used, or three or more types of ink compositions may be used.
When two types of ink compositions are used, two types of ink compositions in which the relationship between the ink composition A and the ink composition B is established are used.
When three or more ink compositions are used, when two ink compositions are arbitrarily selected, one of them becomes ink composition A and the other becomes ink composition B. It is sufficient that at least two kinds of ink compositions are established among the above ink compositions. When three or more types of ink compositions are used, when two types of ink compositions are arbitrarily selected, one of them becomes ink composition A and the other becomes ink composition B. It is preferable to use three or more ink compositions that are established in the ink composition.

(Coloring agent)
The ink composition A contains at least one colorant.
The colorant in the ink composition A is preferably contained outside the microcapsules.
There is no restriction | limiting in particular as a coloring agent, It can select from well-known color materials, such as a pigment, a water-soluble dye, a disperse dye, and can use it. Among these, it is more preferable to include a pigment from the viewpoint of excellent weather resistance and rich color reproducibility.

The pigment is not particularly limited and may be appropriately selected depending on the purpose. Examples thereof include known organic pigments and inorganic pigments. Resin particles dyed with dyes, commercially available pigment dispersions and surfaces Treated pigments (for example, pigments dispersed in water, liquid compounds, insoluble resins, etc., and pigment surfaces treated with resins, pigment derivatives, etc.) are also included.
Examples of organic pigments and inorganic pigments include yellow pigments, red pigments, magenta pigments, blue pigments, cyan pigments, green pigments, orange pigments, purple pigments, brown pigments, black pigments, and white pigments.
When a pigment is used as the colorant, a pigment dispersant may be used as necessary when preparing the pigment particles.

  Regarding color materials such as pigments and pigment dispersants, paragraphs 0180 to 0200 of JP-A No. 2014-040529 can be appropriately referred to.

The absorbance ABS _A of the ink composition _A is determined by the type and content of the colorant.
As the colorant in the ink composition A, yellow pigments, magenta pigments, and cyan pigments are preferable, and quinacridone pigments, copper phthalocyanine pigments, monoazo pigments, and disazo pigments are more preferable.
When the colorant of the ink composition A is the above pigment, the absorbance ABS _A can be easily adjusted.

Examples of quinacridone pigments include C.I. I. Pigment Red 122, 202 (including a mixture with CI Pigment Violet 19), 207, 209 and the like.
Examples of copper phthalocyanine pigments include C.I. I. Pigment blue 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 16, 17: 1, 75, 79, and the like.
Examples of monoazo pigments include C.I. I. Pigment yellow 1, 2, 3, 4, 5, 10, 65, 73, 74, 75, 97, 98, 111, 116, 130, 167, 205 and the like.
Examples of the disazo pigment include C.I. I. Pigment yellow 2, 13, 14, 16, 17, 55, 63, 77, 81, 83, 106, 124, 126, 127, 152, 155, 170, 172, 174, 176, 214, 219, and the like.

(Carbon black)
The ink composition B contains at least one carbon black.
The carbon black in the ink composition B is preferably contained outside the microcapsules.
There is no restriction | limiting in particular as carbon black, It can select and use arbitrarily from well-known carbon black.
The absorbance ABS _B of the ink composition _B is determined by the type and content of carbon black.

  Examples of the carbon black include those produced by known methods such as a contact method, a furnace method, and a thermal method.

  Examples of commercially available carbon blacks include Raven7000, Raven5750, Raven5250, Raven500 ULTRAII, Raven3500, Raven2000, Raven1500, Raven1250, Raven1200, Raven1190, Raven1170, Raven10, Raven10, Raven10, Raven10 (Registered trademark, manufactured by Colombian Carbon), Regal 400R, Regal 330R, Regal 660R, Mogu L, Black Pearls L, Monarch 700, Monarch 800, Monarch 880, Monarch 900, Monarch 1000, Monar h 1100, Monarch 1300, Monarch 1400, etc. (all “Monarch” is a registered trademark, manufactured by Cabot Corporation), Color Black FW1, Color Black FW2, Color Black FW2V, Color Black 18, Color Black 18, Color Black 18 Black S150, Color Black S160, Color Black S170, Printex35, Printex U, Printex V, Printex140U, Printex140V, Special Black 6, Ack, A4 Manufactured by Zinniad Carbons Co., Ltd. 25, no. 33, no. 40, no. 45, no. 47, no. 52, no. 900, no. 2200B, no. 2300, MCF-88, MA600, MA7, MA8, MA100 and the like (manufactured by Mitsubishi Chemical Corporation).

The content of the colorant in the ink composition A and the content of carbon black in the ink composition B can be selected as appropriate, but are 0.1% by mass to 30% with respect to the total mass of each ink composition. % By mass is preferable, 0.5% by mass to 20% by mass is more preferable, and 1.0% by mass to 10% by mass is more preferable.
In particular, the carbon black content in the ink composition B is 1.5% by mass to 2.5% by mass of carbon black with respect to the total mass of the ink composition B from the viewpoint of color bleeding and granularity. preferable.

  When the ink composition A contains a quinacridone pigment as a colorant, the ink composition A contains 4.0% by mass to 6.0% by mass of a quinacridone pigment with respect to the total mass of the ink composition A, and the ink composition More preferably, the product B contains 1.5% to 3.0% by mass of carbon black with respect to the total mass of the ink composition B, and the ink composition A is 4% with respect to the total mass of the ink composition A. The ink composition B contains 1.5% by mass to 2.5% by mass of carbon black with respect to the total mass of the ink composition B. Further preferred.

  When the ink composition A contains a copper phthalocyanine pigment as a colorant, the ink composition A contains 1.7% by mass to 3.1% by mass of a copper phthalocyanine pigment with respect to the total mass of the ink composition A; More preferably, the ink composition B contains 1.5% by mass to 3.0% by mass of carbon black based on the total mass of the ink composition B, and the ink composition A is based on the total mass of the ink composition A. 1.7 wt% to 3.1 wt% of a copper phthalocyanine pigment, and ink composition B contains 1.5 wt% to 2.5 wt% of carbon black with respect to the total weight of ink composition B. More preferably.

  When the ink composition A includes a monoazo pigment as a colorant, the ink composition A includes 3.0% by mass to 4.5% by mass of the monoazo pigment with respect to the total mass of the ink composition A, and the ink composition B Is more preferable to contain 1.5% by mass to 3.0% by mass of carbon black with respect to the total mass of the ink composition B, and the ink composition A is 3.0% with respect to the total mass of the ink composition A. More preferably, the ink composition B contains 1.5% to 2.5% by mass of carbon black with respect to the total mass of the ink composition B.

(High boiling point solvent)
The ink composition contains at least one high boiling point solvent.
The ink composition contains a high-boiling solvent, and after discharging the ink composition onto the substrate, a drying process is performed to evaporate water in the ink composition, increasing the concentration of the high-boiling solvent, The capsules agglomerate. Therefore, the ink composition is fixed on the substrate.
Concentration M _B of the high-boiling solvent in a concentration M _A and ink composition B of the high-boiling solvent in the ink composition A is as described above.

The high boiling point solvent means a solvent having a boiling point exceeding 100 ° C.
The boiling point of the high boiling point solvent is more than 100 ° C and preferably 400 ° C or less, more preferably 150 ° C or more and 300 ° C or less, and further preferably 180 ° C or more and 280 ° C or less.
When the boiling point exceeds 100 ° C., the discharge property is excellent. On the other hand, when the boiling point is 400 ° C. or lower, the film strength is excellent.
The boiling point can be measured by a vapor pressure measurement method (edited by Organic Synthesis Research Group, “New Edition Solvent Pocket Book”, p. 48, Ohm (1994)).

The high boiling point solvent is preferably a water-soluble solvent from the viewpoint of the cohesiveness of the microcapsules.
The “water-soluble solvent” means a solvent having a dissolution amount of more than 1 g in 100 g of distilled water at 25 ° C.

Hereinafter, specific examples of the high boiling point solvent will be shown. In addition, the numerical value in a parenthesis shows a boiling point (unit: ° C).
Examples of the high boiling point solvent include propylene glycol (188 ° C.), triethylene glycol (276 ° C.), propylene glycol-1-monobutyl ether (170 ° C.), glycerin (290 ° C.), 2-pyrrolidone (245 ° C.), and diethylene glycol. (245 ° C), triethylene glycol (285 ° C), dipropylene glycol (232 ° C), 1,2-hexanediol (223 ° C), diethylene glycol monoethyl ether (202 ° C), diethylene glycol diethyl ether (230 ° C), etc. Can be mentioned.
Among the above solvents, it is preferable to use a combination of a solvent having a boiling point of 200 ° C. or lower and a solvent having a boiling point exceeding 200 ° C. from the viewpoint of achieving both ink jet discharge properties and abrasion resistance.

(Micro capsule)
The ink composition includes at least one kind of microcapsules enclosing at least a polymerizable compound.
The microcapsule has a structure having a shell that is an outermost shell and a core that is an area enclosed by the shell, and the core includes a polymerizable compound.
The microcapsule is confirmed by applying and drying the ink composition containing the microcapsule on a substrate to obtain a sample for morphology observation, then cutting the sample and observing the cut surface with an electron microscope or the like. it can.
More preferably, the microcapsule has a shell having a three-dimensional cross-linking structure including at least one bond selected from urethane bonds and urea bonds, and a core including a polymerizable compound encapsulated in the shell.

  The ink composition is immobilized on the substrate by including microcapsules. Specifically, when the water contained in the ink composition evaporates in the heating step and the concentration of the high boiling point solvent increases, the zeta potential of the ink composition decreases and is dispersed by charge repulsion on the surface. The charge repulsion is weakened, the microcapsules are aggregated, and the ink composition is thickened to be immobilized on the substrate.

The microcapsules contained in the ink composition have the same composition (for example, if the microcapsules contained in the ink composition A contain a polymerizable compound in the core, the microcapsules contained in the ink composition B are also the ink composition A). In the same core as the polymerizable compound contained in the composition). The microcapsules having the same composition refer to those having the same component constituting the shell and containing the same polymerizable compound component in the core. However, the content of each component in the shell and the core may not be the same.
When the microcapsules contained in the ink composition A and the microcapsules contained in the ink composition B have the same composition, the film strength of the ink composition can be easily controlled by the concentration of the microcapsules contained in the ink composition. Further, it is possible to suppress the manufacturing cost and raw material cost when manufacturing the ink.
From the same viewpoint as described above, the microcapsules contained in the ink composition A and the ink composition B are the same microcapsules (having the same composition and containing the same component). Is more preferable.

-Microcapsule core-
The microcapsule is encapsulated in a shell described later and has a core containing a polymerizable compound. The core may contain components such as a photopolymerization initiator and a sensitizer in addition to the polymerizable compound.

--- Inclusion rate ---
Here, the encapsulation rate (mass%) of the polymerizable compound or the like is included in the core of the microcapsule with respect to the total amount of the polymerizable compound or the like in the ink composition when the ink composition containing the microcapsule is prepared. Means the amount of the polymerizable compound or the like (encapsulated in the microcapsule), and indicates the value obtained as follows. Here, a polymerizable compound will be described as an example.

--Measurement method of encapsulation rate (% by mass) of polymerizable compound--
The following operation is performed under the condition of a liquid temperature of 25 ° C.
The following operation is performed on the ink composition from which the colorant or carbon black has been removed by removing the colorant or carbon black from the ink composition by centrifugation (ie, an aqueous dispersion of microcapsules).
First, an aqueous dispersion which is a measurement target of the inclusion ratio (% by mass) of the polymerizable compound was prepared, and two samples of the same mass (hereinafter, “Sample 1” and “Sample 2”) were prepared from the prepared aqueous dispersion. ) Collect.
To sample 1, 100 mass times tetrahydrofuran (THF) with respect to the total solid content in sample 1 is added and mixed to prepare a diluted solution. The obtained diluted solution is centrifuged at 80,000 rpm (round per minute; hereinafter the same) for 40 minutes. A supernatant liquid (hereinafter referred to as “supernatant liquid 1”) generated by centrifugation is collected. By this operation, all the polymerizable compounds contained in the sample 1 are considered to be extracted into the supernatant liquid 1. The mass of the polymerizable compound contained in the collected supernatant liquid 1 is measured by liquid chromatography (for example, a liquid chromatography apparatus manufactured by Waters). The mass of the resulting polymerizable compound is defined as “total amount of polymerizable compound”.
Further, the sample 2 is subjected to centrifugal separation under the same conditions as the centrifugal separation performed on the diluent. A supernatant liquid (hereinafter referred to as “supernatant liquid 2”) generated by centrifugation is collected. By this operation, it is considered that the polymerizable compound not encapsulated in the microcapsule (that is, free) in Sample 2 is extracted into the supernatant 2. The mass of the polymerizable compound contained in the collected supernatant liquid 2 is measured by liquid chromatography (for example, a liquid chromatography apparatus manufactured by Waters). The mass of the obtained polymerizable compound is defined as “free amount of polymerizable compound”.
Based on the “total amount of polymerizable compound” and the “free amount of polymerizable compound”, the encapsulation rate (% by mass) of the polymerizable compound is determined according to the following formula.
Inclusion rate of polymerizable compound (% by mass) = ((total amount of polymerizable compound−free amount of polymerizable compound) / total amount of polymerizable compound) × 100

  When the ink composition contains two or more polymerizable compounds, the total amount of the two or more polymerizable compounds is defined as “total amount of polymerizable compounds”, and the total amount of free amounts of the two or more polymerizable compounds is expressed as “ As the “free amount of the polymerizable compound”, the inclusion ratio of the two or more polymerizable compounds may be obtained, and the amount of any one of the polymerizable compounds is defined as “the total amount of the polymerizable compounds”, and any one of the above polymerizations is performed. The encapsulating rate of any one of the above polymerizable compounds may be determined by setting the free amount of the polymerizable compound as the “free amount of the polymerizable compound”.

Whether or not a component other than the polymerizable compound is encapsulated in the microcapsule can also be confirmed by a method similar to the method for examining whether or not the polymerizable compound is encapsulated.
However, for compounds having a molecular weight of 1,000 or more, the masses of the compounds contained in the above supernatant liquid 1 and supernatant liquid 2 were measured by gel permeation chromatography (GPC). The amount of inclusion (mass%) of the compound is determined.

In the measurement by gel permeation chromatography (GPC), HLC (registered trademark) -8020GPC (Tosoh Corp.) was used as a measuring device, and TSKgel (registered trademark) Super Multipore HZ-H (4.6 mmID ×) was used as a column. 15 cm, Tosoh Corp.) can be used and THF (tetrahydrofuran) can be used as an eluent. Measurement conditions are as follows: the sample concentration is 0.45 mass%, the flow rate is 0.35 ml / min, the sample injection amount is 10 μl, the measurement temperature is 40 ° C., and a differential refractive index (RI) detector is used. be able to.
The calibration curve is “Standard sample TSK standard, polystyrene” of Tosoh Corporation: “F-40”, “F-20”, “F-4”, “F-1”, “A-5000”, “A -2500 "," A-1000 ", and" n-propylbenzene ".

When the microcapsule encapsulates the photopolymerization initiator, the encapsulation rate of the polymerizable compound can be measured by the same method for the encapsulation rate of the photopolymerization initiator.
The encapsulation rate (% by mass) of the photopolymerization initiator in the ink composition is preferably 10% by mass or more, more preferably 50% by mass or more, and 70% by mass or more from the viewpoint of film curing sensitivity. Is more preferably 80% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, still more preferably 97% by mass or more, and particularly preferably 99% by mass or more.
When two or more types of photopolymerization initiators are contained in the ink composition, it is preferable that the encapsulation rate of at least one photopolymerization initiator is in the above range.

-Polymerizable compound-
The core of the microcapsule contains a polymerizable compound (that is, a compound having a polymerizable group). A polymeric compound may be used only by 1 type and may use 2 or more types together.
It is advantageous from the viewpoint of improving the curing sensitivity of the film and the hardness of the film because the core contains the polymerizable compound. In particular, when the core contains two or more polymerizable compounds and contains a bifunctional or lower polymerizable compound and a trifunctional or higher polymerizable compound, the hardness of the film formed by the ink composition and the film and substrate It is preferable because the adhesiveness can be compatible.
The polymerizable group of the polymerizable compound functions as a polymerizable group that the microcapsule has.
When the microcapsules have a polymerizable group, adjacent microcapsules can be bonded to each other to form a film by irradiation with active energy rays.
The polymerizable group is not particularly limited as long as it is a group capable of causing a polymerization reaction. As the polymerizable group, a group containing an ethylenic double bond is preferable, and a group containing at least one of a vinyl group and a 1-methylvinyl group is more preferable. As the polymerizable group, a (meth) acryloyl group is particularly preferable from the viewpoints of polymerization reactivity and the hardness of the formed film.
The polymerizable group is preferably present on the surface portion of the microcapsule (for example, when the microcapsule is dispersed by a dispersion medium, the portion in contact with the dispersion medium).
The polymerizable group can be confirmed by, for example, Fourier transform infrared spectroscopy (FT-IR) analysis.

  The content of the polymerizable compound contained in the core of the microcapsule (the total amount when two or more types are included) is 30% by mass with respect to the total solid content of the microcapsule from the viewpoint of coexistence of adhesion and film strength. -75 mass% is preferable, 35 mass% -65 mass% is more preferable, 35 mass% -60 mass% is still more preferable.

When the polymerizable compound includes a bifunctional or lower functional polymerizable compound and a trifunctional or higher functional polymerizable compound, the proportion of the bifunctional or lower functional polymerizable compound is a bifunctional or lower functional polymerizable compound and a trifunctional or higher functional polymerizable compound. The total mass is preferably 50% by mass to 90% by mass, more preferably 50% by mass to 80% by mass, and still more preferably 55% by mass to 65% by mass.
Adhesiveness is more excellent when the ratio of the bifunctional or lower polymerizable compound is 50% by mass or more. On the other hand, when the proportion of the bifunctional or lower polymerizable compound is 90% by mass or less, the strength of the film is more excellent.

  The polymerizable compound contained in the core of the microcapsule may be any of a polymerizable monomer, a polymerizable oligomer, and a polymerizable polymer. However, the polymerizable compound easily moves in the microcapsule and has a polymerizable group adjacent to the polymerizable group. A polymerizable monomer is preferable from the viewpoint of being easily disposed at a position where it easily reacts with a group.

The molecular weight of the polymerizable compound is preferably from 100 to 100,000, more preferably from 100 to 10,000, even more preferably from 100 to 4000, even more preferably from 100 to 2000, and particularly preferably as a weight average molecular weight. Is 100-1000.
The weight average molecular weight can be measured by the above-described gel permeation chromatography (GPC).

--Polymerizable monomer--
When the polymerizable compound is a polymerizable monomer, the polymerizable monomer is advantageous from the viewpoint of improving the curing sensitivity of the film and the hardness of the film.
In particular, it is preferable that the core contains a bifunctional or lower polymerizable monomer and a trifunctional or higher functional monomer as the polymerizable compound, since the hardness and adhesion of the film are further improved.
Polymerizable monomers that can be contained in the core of the microcapsule (hereinafter also referred to as inclusion polymerizable monomers) include polymerizable monomers having an ethylenically unsaturated bond that can be radically polymerized (that is, radically polymerizable monomers) and cationically polymerizable monomers. It can be selected from polymerizable monomers having a cationic polymerizable group (that is, a cationic polymerizable monomer).

Examples of the radical polymerizable monomer include acrylate compounds, methacrylate compounds, styrene compounds, vinyl naphthalene compounds, N-vinyl heterocyclic compounds, unsaturated polyesters, unsaturated polyethers, unsaturated polyamides, and unsaturated urethanes.
The radical polymerizable monomer is preferably a compound having an ethylenically unsaturated group.
A radically polymerizable monomer may be used individually by 1 type, and may use 2 or more types together.

  Examples of the acrylate compound include 2-hydroxyethyl acrylate, butoxyethyl acrylate, carbitol acrylate, cyclohexyl acrylate, tetrahydrofurfuryl acrylate, benzyl acrylate, tridecyl acrylate, 2-phenoxyethyl acrylate (PEA), bis (4-acrylic). Loxypolyethoxyphenyl) propane, oligoester acrylate, epoxy acrylate, isobornyl acrylate (IBOA), dicyclopentenyl acrylate, dicyclopentenyloxyethyl acrylate, dicyclopentanyl acrylate, cyclic trimethylolpropane formal acrylate, 2- (2-Ethoxyethoxy) ethyl acrylate, 2- (2-vinyloxyethoxy) ethyl acetate Rate, octyl acrylate, decyl acrylate, isodecyl acrylate, lauryl acrylate, 3,3,5-trimethylcyclohexyl acrylate, 4-t-butylcyclohexyl acrylate, isoamyl acrylate, stearyl acrylate, isoamylstil acrylate, isostearyl acrylate, 2-ethylhexyl Diglycol acrylate, 2-hydroxybutyl acrylate, 2-acryloyloxyethyl hydrophthalic acid, ethoxydiethylene glycol acrylate, methoxydiethylene glycol acrylate, methoxypolyethylene glycol acrylate, methoxypropylene glycol acrylate, 2-hydroxy-3-phenoxypropyl acrylate, vinyl ether acrylate Substitutions such as 2-acryloyloxyethylsuccinic acid, 2-acryloyloxyphthalic acid, 2-acryloxyethyl-2-hydroxyethylphthalic acid, lactone-modified acrylate, acryloylmorpholine, acrylamide, and N-methylolacrylamide, and diacetoneacrylamide Monofunctional acrylate compounds such as acrylamide;

  Polyethylene glycol diacrylate, polypropylene glycol diacrylate, polytetramethylene glycol diacrylate, 1,3-butylene glycol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate (HDDA), 1,9 Nonanediol diacrylate (NDDA), 1,10-decanediol diacrylate (DDDA), 3-methylpentadiol diacrylate (3MPDDA), neopentyl glycol diacrylate, tricyclodecane dimethanol diacrylate, bisphenol A ethylene oxide ( EO) adduct diacrylate, bisphenol A propylene oxide (PO) adduct diacrylate, ethoxylated bisphenol A diacrylate, hydroxy Pineopentyl glycol diacrylate, propoxylated neopentyl glycol diacrylate, alkoxylated dimethylol tricyclodecane diacrylate, and polytetramethylene glycol diacrylate, alkoxylated cyclohexanone dimethanol diacrylate, alkoxylated hexanediol diacrylate, dioxane glycol Diacrylate, cyclohexanone dimethanol diacrylate, diethylene glycol diacrylate, and neopentyl glycol diacrylate, tetraethylene glycol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate (TPGDA), neopentyl glycol propylene oxide adduct diacrylate Bifunctional acryl Doo compounds;

  Trimethylolpropane triacrylate, pentaerythritol triacrylate, dipentaerythritol tetraacrylate, ethoxylated isocyanuric acid triacrylate, ε-caprolactone modified tris- (2-acryloxyethyl) isocyanurate, ditrimethylolpropane tetraacrylate, dipentaerythritol penta Acrylate, dipentaerythritol hexaacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated trimethylolpropane triacrylate, caprolactone modified trimethylolpropane triacrylate, pentaerythritol tetraacrylate, pentaerythritol ethoxytetraacrylate, glycerin propoxytriacrylate, ethoxylated Dipentaellis Examples thereof include tri- or higher functional acrylate compounds such as lithol hexaacrylate, caprolactam-modified dipentaerythritol hexaacrylate, propoxylated glycerin triacrylate, ethoxylated trimethylolpropane triacrylate, and propoxylated trimethylolpropane triacrylate.

  Examples of the methacrylate compound include methyl methacrylate, n-butyl methacrylate, allyl methacrylate, glycidyl methacrylate, benzyl methacrylate, dimethylaminomethyl methacrylate, methoxypolyethylene glycol methacrylate, methoxytriethylene glycol methacrylate, hydroxyethyl methacrylate, phenoxyethyl methacrylate, and cyclohexyl methacrylate. Monofunctional methacrylate compounds such as

  A bifunctional methacrylate compound such as polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, 2,2-bis (4-methacryloxypolyethoxyphenyl) propane, tetraethylene glycol dimethacrylate, and the like can be given.

  Examples of the styrene compound include styrene, p-methylstyrene, p-methoxystyrene, β-methylstyrene, p-methyl-β-methylstyrene, α-methylstyrene, and p-methoxy-β-methylstyrene. .

  Examples of the vinyl naphthalene compound include 1-vinyl naphthalene, methyl-1-vinyl naphthalene, β-methyl-1-vinyl naphthalene, 4-methyl-1-vinyl naphthalene, and 4-methoxy-1-vinyl naphthalene. .

  Examples of N-vinyl heterocyclic compounds include N-vinyl carbazole, N-vinyl pyrrolidone, N-vinyl ethyl acetamide, N-vinyl pyrrole, N-vinylphenothiazine, N-vinyl acetanilide, N-vinyl ethyl acetamide, N- Examples include vinyl succinimide, N-vinyl phthalimide, N-vinyl caprolactam, and N-vinyl imidazole.

  Examples of other radically polymerizable monomers include N-vinylamides such as allyl glycidyl ether, diallyl phthalate, triallyl trimellitate, and N-vinylformamide.

Among these radical polymerizable monomers, bifunctional or lower polymerizable monomers include 1,6-hexanediol diacrylate (HDDA), 1,9-nonanediol diacrylate (NDDA), and 1,10-decanediol diacrylate. (DDDA), 3-methylpentadiol diacrylate (3MPDDA), neopentyl glycol diacrylate, tricyclodecane dimethanol diacrylate, diethylene glycol diacrylate, tetraethylene glycol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate (TPGDA), cyclohexanone dimethanol diacrylate, alkoxylated hexanediol diacrylate, polyethylene glycol diacrylate, polyp At least one selected from propylene glycol diacrylate are preferable.
Examples of the tri- or higher functional polymerizable monomer include trimethylolpropane triacrylate, pentaerythritol triacrylate, dipentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, ethoxylated triacrylate. Methylolpropane triacrylate, propoxylated trimethylolpropane triacrylate, caprolactone modified trimethylolpropane triacrylate, pentaerythritol tetraacrylate, pentaerythritol ethoxytetraacrylate, glycerin propoxytriacrylate, ethoxylated dipentaerythritol hexaacrylate, caprolactam modified dipentaeryth Rito Hexaacrylate, propoxylated glycerol triacrylate, ethoxylated trimethylolpropane triacrylate, and propoxylated at least one selected from trimethylolpropane triacrylate are preferred.

The combination of a bifunctional or lower radical polymerizable monomer and a trifunctional or higher radical polymerizable monomer is preferably a combination of a bifunctional or lower acrylate compound and a trifunctional or higher acrylate compound, preferably a bifunctional acrylate compound and a trifunctional or higher functional acrylate compound. A combination of acrylate compounds is more preferable, a combination of bifunctional acrylate compounds and 3-8 functional acrylate compounds is more preferable, and a combination of bifunctional acrylate compounds and 3-6 functional acrylate compounds is still more preferable.
Furthermore, as a bifunctional acrylate compound, 1,6-hexanediol diacrylate (HDDA), 1,9-nonanediol diacrylate (NDDA), 1,10-decanediol diacrylate (DDDA), 3-methylpentadiol Diacrylate (3MPDDA), neopentyl glycol diacrylate, tricyclodecane dimethanol diacrylate, diethylene glycol diacrylate, tetraethylene glycol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate (TPGDA), cyclohexanone dimethanol diacrylate , At least one selected from polyethylene glycol diacrylate, polypropylene glycol diacrylate, and trifunctional to hexafunctional As acrylate compounds, trimethylolpropane triacrylate, pentaerythritol triacrylate, dipentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated triacrylate Methylolpropane triacrylate, pentaerythritol tetraacrylate, pentaerythritol ethoxytetraacrylate, glycerin propoxytriacrylate, ethoxylated dipentaerythritol hexaacrylate, caprolactam modified dipentaerythritol hexaacrylate, propoxylated glycerin triacrylate, ethoxylated It is most preferred to combine at least one selected trimethylolpropane triacrylate, and propoxylated trimethylolpropane triacrylate.

Examples of the cationic polymerizable monomer include epoxy compounds, vinyl ether compounds, and oxetane compounds.
The cationically polymerizable monomer is preferably a compound having at least one olefin, thioether, acetal, thioxan, thietane, aziridine, N, O, S or P heterocycle, aldehyde, lactam or cyclic ester group.
A cationically polymerizable monomer may be used individually by 1 type, and may use 2 or more types together.

  Examples of the epoxy compound include 1,4-butanediol diglycidyl ether, 3- (bis (glycidyloxymethyl) methoxy) -1,2-propanediol, limonene oxide, 2-biphenylglycidyl ether, and 3,4-epoxy. Cyclohexylmethyl-3 ′, 4′-epoxycyclohexanecarboxylate, epoxide derived from epichlorohydrin-bisphenol S, epoxidized styrene, epoxide derived from epichlorohydrin-bisphenol F, epoxide derived from epichlorohydrin-bisphenol A , Epoxidized novolac, and alicyclic polyepoxides and other bifunctional or lower epoxy compounds.

  Examples of the alicyclic diepoxide include a copolymer of an epoxide and a compound containing a hydroxyl group such as glycol, polyol, and vinyl ale. Specifically, 3,4-epoxycyclohexylmethyl-3 ′, 4′-epoxycycloethyl carbonate, bis (3,4-epoxyhexylmethyl) adipate, limonene diepoxide, and diglycidyl ester of hexahydrophthalic acid Can be mentioned.

  Other epoxy compounds include polyglycidyl esters of polybasic acids, polyglycidyl ethers of polyols, polyglycidyl ethers of polyoxyalkylene glycols, polyglycidyl esters of aromatic polyols, urethane polyepoxy compounds, and polyepoxy polybutadienes. These trifunctional or higher functional epoxy compounds.

Examples of the vinyl ether compound include ethyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, octadecyl vinyl ether, cyclohexyl vinyl ether, butanediol divinyl ether, hydroxybutyl vinyl ether, cyclohexane dimethanol monovinyl ether, phenyl vinyl ether, p-methylphenyl vinyl ether, p- Methoxyphenyl vinyl ether, methyl vinyl ether, β-methyl vinyl ether, β-chloroiso vinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, dodecyl vinyl ether, diethylene glycol monovinyl ether, cyclohexane dimethyl Tanol divinyl ether, 4- (vinyloxy) butylbenzoate, bis [4- (vinyloxy) butyl] adipate, bis [4- (vinyloxy) butyl] succinate, 4- (vinyloxymethyl) cyclohexylmethylbenzoate, bis [4- ( Vinyloxy) butyl] isophthalate, bis [4- (vinyloxymethyl) cyclohexylmethyl] glutarate, 4- (vinyloxy) butyl steatite, bis [4- (vinyloxy) butyl] hexadiyl dicarbamate, bis [4- (vinyloxy ) Methyl] cyclohexyl] methyl] terephthalate, bis [4- (vinyloxy) methyl] cyclohexyl] methyl] isophthalate, bis [4- (vinyloxy) butyl] (4-methyl-1,3-phenylene) -biscal Formate, bis [4-vinyloxy) butyl] (methylenedi-4,1-phenylene) bis carbamate, and 3-amino-1-bifunctional following vinyl ether compounds such as propanol vinyl ether;
Trifunctional or higher functional vinyl ether compounds such as tris [4- (vinyloxy) butyl] trimellitate are exemplified.

  Examples of the oxetane compound include 3-ethyl-3-hydroxymethyl-1-oxetane, 1,4bis [3-ethyl-3-oxetanylmethoxy) methyl] benzene, 3-ethyl-3-phenoxymethyl-oxetane, and bis. ([1-ethyl (3-oxetanyl)] methyl) ether, 3-ethyl-3-[(2-ethylhexyloxy) methyl] oxetane, 3-ethyl-[(triethoxysilylpropoxy) methyl] oxetane, and 3, 3-dimethyl-2- (p-methoxyphenyl) -oxetane.

In addition to the radically polymerizable monomers listed above, Shinzo Yamashita, “Cross-linking agent handbook” (Taishosha, 1981); Kato Kiyomi, “UV / EB curing handbook (raw material)” (1985, Polymer Publications); Rad-Tech Study Group, “Application and Market of UV / EB Curing Technology”, p. 79, (1989, CMC); Eiichiro Takiyama, “Polyester Resin Handbook”, (1988, Nikkan Kogyo) Commercially available products described in newspapers) and the like, or radically polymerizable and crosslinkable monomers known in the industry can be used.
In addition to cationically polymerizable monomers other than those listed above, JV Crivello et al. “Advances in Polymer Science”, 62, pages 1-47 (1984), Lee et al. “Handbook of Epoxy Resins”, McGraw Hill. The compounds described in Book Company, New York (1967), and “Epoxy Resin Technology” (1968) by PF Bruins et al. Can be used.

  Examples of the polymerizable monomer include JP-A-7-159983, JP-B-7-31399, JP-A-8-224982, JP-A-10-863, JP-A-9-134011, The photocurable polymerizable monomer used for the photopolymerizable composition described in each publication such as JP-T-2004-514014 is known, and these can also be applied to microcapsules.

Moreover, as a polymerizable monomer, you may use the commercial item marketed, for example, AH-600 (bifunctional), AT-600 (bifunctional), UA-306H (hexafunctional), UA-306T ( 6 functional), UA-306I (6 functional), UA-510H (10 functional), UF-8001G (2 functional), DAUA-167 (2 functional) (Kyoeisha Chemical Co., Ltd.), SR339A (PEA, monofunctional), SR506 (IBOA, monofunctional), CD262 (bifunctional), SR238 (HDDA, bifunctional), SR341 (3MPDDA, bifunctional), SR508 (bifunctional), SR306H (bifunctional), CD560 (bifunctional), SR833S ( Bifunctional), SR444 (trifunctional), SR454 (trifunctional), SR492 (trifunctional), SR499 (trifunctional), CD501 (trifunctional), SR 02 (trifunctional), SR9020 (trifunctional), CD9021 (trifunctional), SR9035 (trifunctional), SR494 (tetrafunctional), SR399E (pentafunctional) (SARTOMER), A-NOD-N (bifunctional NDDA) A-DOD-N (bifunctional, DDDA), A-200 (bifunctional), APG-400 (bifunctional), A-BPE-10 (bifunctional), A-BPE-20 (bifunctional), A -9300 (trifunctional), A-9300-1CL (trifunctional), A-TMPT (trifunctional), A-TMM-3L (trifunctional), A-TMMT (tetrafunctional), AD-TMP (tetrafunctional) (Shin Nakamura Chemical Co., Ltd.), UV-7510B (Trifunctional) (Nippon Synthetic Chemical Co., Ltd.), KAYARAD DCPA-30 (hexafunctional), KAYARAD DPEA-12 (hexafunctional) (Nippon Kayaku Co., Ltd.) Light Acrylate NPA (2 functional), Light Acrylate 3EG-A (2 functional) (Kyoeisha Chemical Co., Ltd.) and the like.
Other polymerizable monomers include NPGPODA (neopentyl glycol propylene oxide adduct diacrylate), SR531, SR285, SR256 (manufactured by SARTOMER), A-DHP (dipentaerythritol hexaacrylate, Shin-Nakamura Chemical Co., Ltd.), Commercial products such as Aronix (registered trademark) M-156 (Toagosei Co., Ltd.), V-CAP (BASF Corp.), Biscote # 192 (Osaka Organic Chemical Co., Ltd.) and the like can be suitably used.

  The polymerizable monomer is produced by dissolving the polymerizable monomer as an oil phase component together with the components constituting the microcapsule when the microcapsule is produced, adding the water phase component to the oil phase component, mixing, and emulsifying. It can be included in the core of the capsule.

The molecular weight of the polymerizable monomer is preferably 100 to 4000, more preferably 100 to 2000, and still more preferably 100 to 1000, as a weight average molecular weight.
The weight average molecular weight can be measured by gel permeation chromatography (GPC).

  In the total solid content of the microcapsule, the content of the polymerizable monomer is preferably 0.1% by mass to 75% by mass, more preferably 0.5% by mass to 60% by mass, and still more preferably, 1% by mass to 50% by mass. By setting it within the above range, an image having good crosslinkability and film strength can be obtained.

--- Polymerizable oligomer and polymerizable polymer--
When the polymerizable compound is a polymerizable oligomer or a polymerizable polymer, it is advantageous from the viewpoint of suppressing a decrease in the adhesion between the film and the substrate by reducing the curing shrinkage of the film.

Examples of the polymerizable oligomer and polymerizable polymer include oligomers and polymers such as acrylic resin, urethane resin, polyester, polyether, polycarbonate, epoxy resin, and polybutadiene.
Further, for example, resins such as epoxy acrylate, aliphatic urethane acrylate, aromatic urethane acrylate, and polyester acrylate may be used.
Among these, from the viewpoint of reducing curing shrinkage, a resin that has both a hard segment and a soft segment and can relieve stress during curing is preferable, and at least one selected from urethane resin, polyester resin, and epoxy resin is particularly preferable. The oligomer or polymer is more preferable.

As the polymerizable group, an ethylenically unsaturated group such as a (meth) acryl group, a vinyl group, an allyl group, and a styryl group, and an epoxy group are preferable. From the viewpoint of polymerization reactivity, a (meth) acryl group, a vinyl group, And at least one group selected from styryl groups is more preferable, and a (meth) acryl group is particularly preferable.
The polymerizable oligomer and the polymerizable polymer may have only one type of polymerizable group or two or more types.

These polymerizable groups can be introduced into the polymer or oligomer by polymer reaction or copolymerization.
For example, a polymer is obtained by utilizing a reaction between a polymer or oligomer having a carboxy group in the side chain and glycidyl methacrylate, or a reaction between a polymer or oligomer having an epoxy group and an ethylenically unsaturated group-containing carboxylic acid such as methacrylic acid. Alternatively, a polymerizable group can be introduced into the oligomer. These groups may be used in combination.

  As the polymerizable oligomer and polymerizable polymer, commercially available products may be used. Examples of commercially available products include acrylic resins such as (ACA) Z200M, (ACA) Z230AA, (ACA) Z251, (ACA) Z254F (above, Daicel Ornex Co., Ltd.), Hitaroid 7975D (Hitachi Chemical Co., Ltd.), etc. ;

  EBECRYL (registered trademark) 8402, EBECRYL (registered trademark) 8405, EBECRYL (registered trademark) 9270, EBECRYL (registered trademark) 8311, EBECRYL (registered trademark) 8701, KRM8667, KRM8528 (above, Daicel Ornex Corp.), CN964 CN9012, CN968, CN996, CN975, CN9782 (above SARTOMER), UV-6300B, UV-7600B, UV-7605B, UV-7620EA, UV-7630B (above, Nippon Synthetic Chemical Industry Co., Ltd.), U- 6HA, U-15HA, U-108A, U-200PA, UA-4200 (above, Shin-Nakamura Chemical Co., Ltd.), Teslac 2300, Hitaloid 4863, Teslac 2328, Teslac 2350, Hitalloy 7902-1 (above, Hitachi Chemical Co., Ltd.), 8UA-017, 8UA-239, 8UA-239H, 8UA-140, 8UA-585H, 8UA-347H, 8UX-015A (above, Taisei Fine Chemical Co., Ltd.), etc. Urethane resin;

  CN294, CN2254, CN2260, CN2271E, CN2300, CN2301, CN2302, CN2303, CN2304 (above, SARTOMER), EBECRYL (registered trademark) 436, EBECRYL (registered trademark) 438, EBECRYL (registered trademark) 446L, EB EC Polyester resins such as 524, EBECRYL (registered trademark) 525, EBECRYL (registered trademark) 811, EBECRYL (registered trademark) 812 (above, Daicel Ornex Co., Ltd.);

Polyether resins such as Blemmer (registered trademark) ADE-400A, Blemmer (registered trademark) ADP-400 (above, NOF Corporation);
Polycarbonate resins such as polycarbonate diol diacrylate (Ube Industries)
Epoxy resins such as EBECRYL (registered trademark) 3708 (Daicel Ornex Co., Ltd.), CN120, CN120B60, CN120B80, CN120E50 (above SARTOMER), and Hitaroid 7851 (Hitachi Chemical Co., Ltd.);
Examples thereof include polybutadiene resins such as CN301, CN303, and CN307 (above, SARTOMER).

-Photopolymerization initiator-
The core of the microcapsule may contain at least one photopolymerization initiator. That is, the microcapsule may contain at least one photopolymerization initiator.
When the core contains a photopolymerization initiator, when the ink composition is irradiated with active energy rays, the sensitivity to the active energy rays is increased, and an image having excellent film strength can be obtained.
In addition, when the microcapsule contains a photopolymerization initiator, a photopolymerization initiator that has been conventionally difficult to use because of high sensitivity but low dispersibility in water or low solubility can be used. . For this reason, when a microcapsule is applied to an ink composition, a highly sensitive aqueous ink composition can be realized as compared with a conventional aqueous ink composition. Further, when the microcapsule includes the photopolymerization initiator, the range of selection of the photopolymerization initiator to be used is widened, and as a result, the range of selection of the light source to be used is also widened. Therefore, the curing sensitivity can be improved as compared with the conventional case.
From the same viewpoint as described above, it is preferable that the microcapsules contained in the ink composition A and the ink composition B both include a photopolymerization initiator.

As a photopolymerization initiator (hereinafter also referred to as an encapsulated photopolymerization initiator) that can be contained in the core of the microcapsule, a known photopolymerization initiator can be appropriately selected.
The photopolymerization initiator is a compound that absorbs light (that is, active energy rays) and generates radicals or cations that are polymerization initiation species.

  Known compounds can be used as the photopolymerization initiator. Preferred examples of the photopolymerization initiator include (a) carbonyl compounds such as aromatic ketones, (b) acylphosphine oxide compounds, (c) aromatic onium salt compounds, (d) organic peroxides, (e) Thio compound, (f) hexaarylbiimidazole compound, (g) ketoxime ester compound, (h) borate compound, (i) azinium compound, (j) metallocene compound, (k) active ester compound, (l) carbon halogen Examples thereof include a compound having a bond and (m) an alkylamine compound.

  The core may contain the above compounds (a) to (m) as a photopolymerization initiator alone or in combination of two or more.

Preferred examples of (a) carbonyl compounds, (b) acylphosphine oxide compounds, and (e) thio compounds include “RADIATION CURING IN POLYMER SCIENCE AND TECHNOLOGY”, J. MoI. P. FOUASSIER, J.A. F. RABEK (1993), pp. Examples include compounds having a benzophenone skeleton or a thioxanthone skeleton described in 77-117.
More preferable examples include α-thiobenzophenone compounds described in JP-B-47-6416, benzoin ether compounds described in JP-B-47-3981, α-substituted benzoin compounds described in JP-B-47-22326, Benzoin derivatives described in JP-B-47-23664, aroylphosphonic acid esters described in JP-A-57-30704, dialkoxybenzophenones described in JP-B-60-26483, JP-B-60-26403, JP-A Benzoin ethers described in JP-A No. 62-81345, JP-B-1-34242, US Pat. No. 4,318,791 pamphlet, α-aminobenzophenones described in European Patent No. 0284561A1, JP-A-2-21152 P-di (dimethylamino) Nzoyl) benzene, thio-substituted aromatic ketone described in JP-A-61-194062, acylphosphine sulfide described in JP-B-2-9597, acylphosphine described in JP-B-2-9596, JP-B-63-61950 Thioxanthones described in Japanese Patent Publication No. JP-A-59-42864, compounds described in International Publication No. 2015/158745, and the like.
In addition, a photopolymerization initiator described in JP 2008-105379 A or JP 2009-114290 A is also preferable.

  Examples of commercially available photopolymerization initiators include IRGACURE (registered trademark) 184, 369, 500, 651, 819, 907, 1000, 1300, 1700, 1870, DAROCUR (registered trademark) 1173, 2959, 4265, ITX, LUCIRIN (registered trademark) TPO (above, all made by BASF), ESACURE (registered trademark) KTO37, KTO46, KIP150, EDB (above, all made by Lamberti), H-Nu (registered trademark) 470, 470X (more, all Spectra Group Limited, Omnipol 9210 (IGM), SpeedCure 7040 (LAMBSON), and the like.

Among these photopolymerization initiators, as the photopolymerization initiator, from the viewpoint of sensitivity to UV light, at least one compound selected from (a) a carbonyl compound and (b) an acylphosphine oxide compound is more preferable. Specifically, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide (for example, IRGACURE (registered trademark) 819 manufactured by BASF), 2- (dimethylamine) -1- (4-morpholinophenyl) 2-benzyl-1-butanone (for example, IRGACURE (registered trademark) 369 manufactured by BASF), 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one (for example, BASF) IRGACURE® 907), 1-hydroxy-cyclohexyl-phenyl-ke (For example, IRGACURE (registered trademark) 184 manufactured by BASF), 2-hydroxy-2-methyl-1-phenyl-propan-1-one (for example, IRGACURE (registered trademark) 1173 manufactured by BASF), 2, Examples include 4,6-trimethylbenzoyl-diphenyl-phosphine oxide (for example, DAROCUR (registered trademark) TPO, LUCIRIN (registered trademark) TPO (both manufactured by BASF)).
Among these, from the viewpoint of compatibility with LED light, as the photopolymerization initiator, (b) acylphosphine oxide compounds are preferable, and monoacylphosphine oxide compounds (particularly preferably 2,4,6-trimethylbenzoyl). -Diphenyl-phosphine oxide) or a bisacylphosphine oxide compound (particularly preferably bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide).

  The photopolymerization initiator is obtained by dissolving the photopolymerization initiator as an oil phase component together with the components constituting the microcapsule, adding the water phase component to the oil phase component, mixing, and emulsifying the microcapsule. Can be included in the core of the microcapsule.

  The content of the photopolymerization initiator is preferably 0.1% by mass to 25% by mass, more preferably 0.5% by mass to 20% by mass, and still more preferably 0.5% by mass with respect to the total solid content of the microcapsule. It is mass%-15 mass%.

When the core of the microcapsule contains a photopolymerization initiator, the content ratio of the photopolymerization initiator to the polymerizable compound in the core is such that the content of the photopolymerization initiator is the content of the polymerizable compound. On the other hand, it is preferable that it is 0.5 mass%-25 mass%.
When the content of the photopolymerization initiator in the core is 0.5% by mass or more with respect to the content of the polymerizable compound, the film strength of the ink composition is further improved. On the other hand, when the content of the photopolymerization initiator in the core is 25% by mass or less with respect to the content of the polymerizable compound, the dischargeability of the ink composition is further improved.
From the same viewpoint as described above, the content of the photopolymerization initiator in the core is preferably 1% by mass to 50% by mass with respect to the content of the polymerizable compound, more preferably 1% by mass to 20% by mass, and more preferably 5% by mass. More preferably, it is 10 mass%.
In particular, the content of the photopolymerization initiator encapsulated in the microcapsules contained in the ink composition A and the ink composition B is preferably in the above range.

-Sensitizer-
The core of the microcapsule may contain at least one sensitizer.
When the core of the microcapsule contains a sensitizer, the decomposition of the photopolymerization initiator by active energy ray irradiation can be further promoted.
A sensitizer is a substance that absorbs specific active energy rays and enters an electronically excited state. The sensitizer brought into the electronically excited state comes into contact with the photopolymerization initiator, and produces effects such as electron transfer, energy transfer, and heat generation. This promotes chemical changes of the photopolymerization initiator, that is, decomposition, generation of radicals, acids or bases, and the like.

Examples of the sensitizer include benzophenone, thioxanthone, isopropylthioxanthone, anthraquinone, 3-acyl coumarin derivatives, terphenyl, styryl ketone, 3- (aroylmethylene) thiazoline, camphorquinone, eosin, rhodamine, erythrosine and the like. .
Examples of the sensitizer include compounds represented by general formula (i) described in JP 2010-24276 A and compounds represented by general formula (I) described in JP 6-107718 A. Can also be suitably used.
Furthermore, compounds described in WO2015 / 158745, specifically tertiary aliphatic amines (eg methyldiethanolamine, dimethylethanolamine, triethanolamine, triethylamine, and N-methylmorpholine); aromatic amines (For example, amyl paradimethylaminobenzoate, 2-butoxyethyl 4- (dimethylamino) benzoate, 2- (dimethylamino) ethyl benzoate, ethyl 4- (dimethylamino) benzoate, and 4- (dimethylamino) 2-ethylhexyl); (meth) acrylated amines [eg, dialkylamino alkyl (meth) acrylates (such as diethylaminoethyl acrylate) and N-alkylmorpholine (meth) acrylates (such as N-alkylmorpholine acrylate)] Well as Can be preferably used.

  Among them, the sensitizer is preferably at least one selected from thioxanthone, isopropylthioxanthone, and benzophenone from the viewpoint of compatibility with LED light and reactivity with a photopolymerization initiator, and is selected from thioxanthone and isopropylthioxanthone. At least one is more preferable, and isopropylthioxanthone is still more preferable.

  When the core of the microcapsule contains a sensitizer, the content of the sensitizer is preferably 0.1% by mass to 25% by mass with respect to the total solid content of the microcapsule, and 0.5% by mass. % To 20% by mass is more preferable, and 1% to 15% by mass is even more preferable.

(Microcapsule shell)
The microcapsule preferably has a shell (hereinafter also simply referred to as “shell”) having a three-dimensional cross-linking structure including at least one type of bond selected from a urethane bond and a urea bond.
In the present specification, the “three-dimensional crosslinked structure” refers to a three-dimensional network structure formed by crosslinking.

When the shell of the microcapsule has a three-dimensional cross-linking structure, it contributes to improvement in dispersion stability and redispersibility when the microcapsule is applied to the ink composition.
The redispersibility means that an aqueous liquid (for example, water, an aqueous solution, an aqueous dispersion, etc.) is supplied to a solidified product formed by evaporation of water in the ink composition. Of the particles (here, microcapsules) are dispersed again in the aqueous liquid. As an example of said solidified material, the solidified material of the ink composition formed in the application | coating head or the inkjet head is mentioned.

Whether or not the shell of the microcapsule has a three-dimensional cross-linked structure is confirmed as follows. The following operation is performed under the condition of a liquid temperature of 25 ° C.
In the following operation, first, the colorant is removed from the ink composition by centrifugation, and the following operation is performed on the ink composition from which the colorant has been removed (that is, an aqueous dispersion of microcapsules).
A sample is taken from the aqueous dispersion. Tetrahydrofuran (THF) 100 mass times the total solid content in the sample is added to the collected sample and mixed to prepare a diluted solution. The obtained diluted solution is centrifuged at 80,000 rpm for 40 minutes. After centrifugation, visually check for residue. When there is a residue, the residue is re-dispersed with water to prepare a re-dispersion, and the obtained re-dispersion is subjected to light scattering using a wet particle size distribution analyzer (LA-960, manufactured by Horiba, Ltd.). The particle size distribution is measured by the method.
When the particle size distribution can be confirmed by the above operation, it is determined that the shell of the microcapsule has a three-dimensional crosslinked structure.

The three-dimensional crosslinked structure of the shell of the microcapsule can be formed, for example, by a reaction between a trifunctional or higher functional isocyanate compound or a bifunctional isocyanate compound and water or a compound having two or more active hydrogen groups.
In particular, when the raw material for producing the microcapsule contains at least one compound having three or more reactive groups (isocyanate group or active hydrogen group), the crosslinking reaction is more effective in three dimensions. As a result, a three-dimensional network structure is formed more effectively.
The three-dimensional crosslinked structure in the microcapsule is preferably a product formed by a reaction between a trifunctional or higher functional isocyanate compound and water.

The three-dimensional crosslinked structure of the shell preferably includes the following structure (1).
The three-dimensional crosslinked structure may include a plurality of the following structures (1), and the plurality of structures (1) may be the same structure or different structures.

In structure (1), X is a hydrocarbon group optionally having a ring structure, —NH—,> N—, —C (═O) —, —O—, and —S—. It represents a (p + m + n) -valent organic group formed by linking at least two selected.
In the structure (1), R ¹ , R ² , and R ³ each independently represent a hydrocarbon group having 5 to 15 carbon atoms that may have a ring structure.
In structure (1), * represents a bonding position, p, m, and n are each 0 or more, and p + m + n is 3 or more.

The total molecular weight of X, R ¹ , R ² , and R ³ is preferably less than 2000, preferably less than 1500, and more preferably less than 1000. When the total molecular weight of X, R ¹ , R ² , and R ³ is less than 2000, the encapsulation rate of the compound encapsulated in the core can be increased.

  The hydrocarbon group in the organic group represented by X is preferably a linear or branched hydrocarbon group having 1 to 15 carbon atoms, and a linear or branched hydrocarbon group having 1 to 10 carbon atoms. Groups are more preferred.

Examples of the ring structure that the hydrocarbon group in the organic group represented by X and the hydrocarbon group represented by R ¹ , R ² , and R ³ may have include an alicyclic structure and an aromatic ring structure Is mentioned.
Examples of the alicyclic structure include a cyclohexane ring structure, a bicyclohexane ring structure, a bicyclodecane ring structure, an isobornene ring structure, a dicyclopentane ring structure, an adamantane ring structure, and a tricyclodecane ring structure.
Examples of the aromatic ring structure include a benzene ring structure, a naphthalene ring structure, and a biphenyl ring structure.

In the structure (1), p is 0 or more, preferably 1 to 10, more preferably 1 to 8, still more preferably 1 to 6, and particularly preferably 1 to 3.
In structure (1), m is 0 or more, 1-10 are preferable, 1-8 are more preferable, 1-6 are still more preferable, and 1-3 are especially preferable.
In structure (1), n is 0 or more, 1-10 are preferable, 1-8 are more preferable, 1-6 are still more preferable, and 1-3 are especially preferable.
In the structure (1), p + m + n is preferably an integer of 3 to 10, more preferably an integer of 3 to 8, and still more preferably an integer of 3 to 6.

  The (p + m + n) -valent organic group represented by X is preferably a group represented by any one of the following (X-1) to (X-12).

In formula (X-1) to formula (X-12), n represents an integer of 1 to 200, preferably an integer of 1 to 50, more preferably an integer of 1 to 15, particularly preferably 1 to 8. Represents an integer.
In formula (X-11) to formula (X-12), * represents a bonding position.
In formula (X-1) to formula (X-10), Y represents the following (Y-1).

In (Y-1), * ¹ represents a bonding position with S or O in (X-1) to (X-10), and * ² represents R ¹ , R ² , or R in structure (1). ³ represents the binding position.

In the structure (1), R ¹ , R ² , and R ³ each independently represent a hydrocarbon group having 5 to 15 carbon atoms that may have a ring structure.
The hydrocarbon group in R ¹ , R ² , and R ³ may have a substituent, and examples of the substituent include a hydrophilic group that the shell can have, which will be described later.

R ¹ , R ² , and R ³ are preferably each independently a group represented by any one of the following (R-1) to (R-20). In (R-1) to (R-20), * indicates a bonding position.

  The content of the structure (1) in the shell is preferably 8% by mass to 100% by mass with respect to the total mass of the shell, more preferably 25% by mass to 100% by mass, and 50% by mass to 100% by mass. Is more preferable.

  The shell preferably includes at least one of the following structures (2), (3), and (4) as the structure (1).

In the structure (2), R ¹ , R ² , and R ³ each independently represent a hydrocarbon group having 5 to 15 carbon atoms that may have a ring structure.
Structure ^(2), the hydrocarbon group represented by R 1, ^{R 2} and ^{R 3} each, the structure of ^(1), R 1, ^{R 2,} and synonymous with hydrocarbon groups represented by ^{R 3} And the preferred range is also the same.
In the structure (2), * represents a bonding position.

In the structure (3), R ¹ , R ² , and R ³ each independently represent a hydrocarbon group having 5 to 15 carbon atoms that may have a ring structure.
Structure ^(3), the hydrocarbon group represented by R 1, ^{R 2} and ^{R 3} each, the structure of ^(1), R 1, ^{R 2,} and synonymous with hydrocarbon groups represented by ^{R 3} And the preferred range is also the same.
In structure (3), * represents a bonding position.

In the structure (4), R ¹ , R ² , and R ³ each independently represent a hydrocarbon group having 5 to 15 carbon atoms that may have a ring structure.
Structure ^(4), the hydrocarbon group represented by R 1, ^{R 2} and ^{R 3} each, the structure of ^(1), R 1, ^{R 2,} and synonymous with hydrocarbon groups represented by ^{R 3} And the preferred range is also the same.
In the structure (4), * represents a bonding position.

  Specific examples of the structures (1) to (4) include the structures shown in Table 1 below.

The three-dimensional crosslinked structure of the shell of the microcapsule can be formed, for example, by a reaction between a trifunctional or higher functional isocyanate compound or a bifunctional isocyanate compound and water or a compound having two or more active hydrogen groups.
In particular, when the raw material for producing the microcapsule contains at least one compound having three or more reactive groups (isocyanate group or active hydrogen group), the crosslinking reaction is more effective in three dimensions. As a result, a three-dimensional network structure is formed more effectively.
The three-dimensional crosslinked structure of the shell of the microcapsule is preferably a product formed by the reaction of a trifunctional or higher functional isocyanate compound and water.

-Isocyanate compound with 3 or more functions-
The trifunctional or higher functional isocyanate compound is a compound having three or more isocyanate groups in the molecule. In the present disclosure, as the trifunctional or higher functional isocyanate compound, any of a compound synthesized by a method described later and a known compound can be used. Examples of the trifunctional or higher functional isocyanate compound include a trifunctional or higher functional aromatic isocyanate compound and a trifunctional or higher functional aliphatic isocyanate compound.
Known compounds include, for example, compounds described in “Polyurethane Resin Handbook” (edited by Keiji Iwata, published by Nikkan Kogyo Shimbun (1987)).

  The trifunctional or higher functional isocyanate compound is preferably a compound having three or more isocyanate groups in the molecule, specifically, a compound represented by the following formula (X).

In formula (X), X ₁ represents an n-valent organic group.
In formula (X), n is 3 or more. n is preferably from 3 to 10, more preferably from 3 to 8, and still more preferably from 3 to 6.

  As the compound represented by the formula (X), a compound represented by the following formula (11) is preferable.

Wherein ^{(11), X, R 1} , R 2, R 3, p, m, and n, ^X in the above structure ^{(1), R 1, R} 2, R 3, p, m, and the n It is synonymous and a preferable aspect is also the same.

The trifunctional or higher functional isocyanate compound is preferably a compound derived from a bifunctional isocyanate compound (a compound having two isocyanate groups in the molecule).
The trifunctional or higher functional isocyanate compound is selected from isophorone diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, m-xylylene diisocyanate, and dicyclohexylmethane-4,4′-diisocyanate. More preferably, it is an isocyanate compound derived from at least one kind.
Here, “derived” means that the above compound is used as a raw material and includes a structure derived from the above isocyanate compound.

In addition, as the trifunctional or higher functional isocyanate compound, for example, a bifunctional isocyanate compound (a compound having two or more isocyanate groups in the molecule) and three trifunctional or higher functional polyols, polyamines, and polythiols in the molecule. Trifunctional or higher functional isocyanate compound (adduct type), bifunctional isocyanate compound trimer (biuret type or isocyanurate type), and benzene isocyanate as adducts (adducts) with compounds having the above active hydrogen groups Also preferred are compounds having three or more isocyanate groups in the molecule, such as the formalin condensate.
These trifunctional or higher functional isocyanate compounds may be a mixture containing a plurality of compounds, and a compound represented by the following formula (11A) or (11B) is a main component of these mixtures. Preferably, other components may be included.

--Adduct type--
The adduct type trifunctional or higher functional isocyanate compound is preferably a compound represented by the following formula (11A) or formula (11B).

In Formula (11A) and Formula (11B), X ² is a (p + m + n) -valent organic group, p, m, and n are each 0 or more, and p + m + n is 3 or more.
In formula (11A) and formula (11B), X ^{3 to} X ¹¹ each independently represents O, S, or NH.
In formula (11A) and formula (11B), R ^{1 to} R ⁶ each independently represents a divalent organic group.
In formula (11A) and formula (11B), Z represents a divalent organic group.

In formula (11A) and formula (11B), X ² is a hydrocarbon group optionally having a ring structure, —NH—,> N—, —C (═O) —, —O—, and A (p + m + n) -valent organic group formed by linking at least two selected from the group consisting of —S— is preferable.
In formula (11A) and formula (11B), as p + m + n, 3-10 are preferable, 3-8 are more preferable, and 3-6 are still more preferable.
In Formula (11A) and Formula (11B), X ^{3 to} X ¹¹ are each independently preferably O or S, and more preferably O.
In formula (11A) and formula (11B), R ^{1 to} R ⁶ are each independently preferably a hydrocarbon group having 5 to 15 carbon atoms which may have a ring structure.
In formula (11A) and formula (11B), preferred embodiments of R ^{1 to} R ⁶ are each independently the same as the preferred embodiment of R ¹ in the structure (1).

In Formula (11A) and Formula (11B), examples of the ring structure when X ² is a hydrocarbon group which may have a ring structure include an alicyclic structure and an aromatic ring structure.
Examples of the alicyclic structure include a cyclohexane ring structure, a bicyclohexane ring structure, a bicyclodecane ring structure, an isobornene ring structure, a dicyclopentane ring structure, an adamantane ring structure, and a tricyclodecane ring structure.
Examples of the aromatic ring structure include a benzene ring structure, a naphthalene ring structure, and a biphenyl ring structure.

In the formula (11A) and the formula (11B), the ring structure in the case where R ^{1 to} R ⁶ are a hydrocarbon group having 5 to 15 carbon atoms which may have a ring structure includes an alicyclic structure, An aromatic ring structure is exemplified.
Examples of the alicyclic structure include a cyclohexane ring structure, a bicyclohexane ring structure, a bicyclodecane ring structure, an isobornene ring structure, a dicyclopentane ring structure, an adamantane ring structure, and a tricyclodecane ring structure.
Examples of the aromatic ring structure include a benzene ring structure, a naphthalene ring structure, and a biphenyl ring structure.

Wherein (11A) and the formula (11B), represented by ^{X 2 (p + m + n} ) valent organic group is a group represented by any one of the following (X2-1) ~ (X2-10) It is preferable.

In formula (X2-1) to formula (X2-10), n represents an integer of 1 to 200, preferably an integer of 1 to 50, more preferably an integer of 1 to 15, particularly preferably 1 to 8. Represents an integer.
In formula (X2-1) to formula (X2-10), * represents a bonding position.

In formula (11B), the divalent organic group represented by Z has a hydrocarbon group, a group having a polyoxyalkylene structure, a group having a polycaprolactone structure, a group having a polycarbonate structure, or a polyester structure. Groups are preferred.
The hydrocarbon group in Z may be a linear hydrocarbon group, a branched chain hydrocarbon group, or a cyclic hydrocarbon group.
The hydrocarbon group in Z preferably has 2 to 30 carbon atoms.

In formula (11A) and formula (11B), R ^{1 to} R ⁶ are each independently preferably a group (R-1) to a group (R-20).

In formula (11A) and formula (11B), R ^{1 to} R ⁶ are each independently preferably a group (R-1) to a group (R-20).
In formula (11A) and formula (11B), R ^{1 to} R ⁶ are each independently a group derived from isophorone diisocyanate (IPDI) (R-3) or a group derived from hexamethylene diisocyanate (HDI). (R-7), a group derived from trimethylhexamethylene diisocyanate (TMHDI) (R-5), a group derived from m-xylylene diisocyanate (XDI) (R-9), 1,3-bis (isocyanate) More preferably, it is either a group (R-1) derived from (methyl) cyclohexane or a group (R-2) derived from dicyclohexylmethane 4,4′-diisocyanate.

  The compound represented by the general formula (11A) is preferably a compound represented by the following formula (11A-1).

Wherein ^(11A-1), R 1, ^{R 2,} and ^{R 3} has the same meaning as ^R 1, ^{R 2,} and ^{R 3} in the formula (11A), and their preferred embodiments are also the same.

The synthesis of an adduct-type trifunctional or higher functional isocyanate compound can be performed by reacting a compound having three or more active hydrogen groups in a molecule described later with a bifunctional isocyanate compound described later. In the present specification, the active hydrogen group means a hydroxy group, a primary amino group, a secondary amino group, or a mercapto group.
The adduct type trifunctional or higher functional isocyanate compound is, for example, heated with stirring a compound having three or more active hydrogen groups in the molecule and a bifunctional isocyanate compound in an organic solvent (50 ° C. to 100 ° C.). Or by stirring at a low temperature (0 ° C. to 70 ° C.) while adding a catalyst such as stannous octylate (Synthesis Scheme 1 below).
In general, the number of moles (number of molecules) of a bifunctional isocyanate compound to be reacted with a compound having three or more active hydrogen groups in the molecule is the number of active hydrogen groups in the compound having three or more active hydrogen groups in the molecule. A bifunctional isocyanate compound having a mole number (number of molecules) of 0.6 times or more with respect to the mole number (the number of equivalents of active hydrogen groups) is used. The number of moles of the bifunctional isocyanate compound is preferably 0.6 times to 5 times the number of moles of the active hydrogen group, more preferably 0.6 times to 3 times, and even more preferably 0.8 times to 2 times. preferable.

--Synthetic scheme 1--

  In addition, adduct-type trifunctional or higher functional isocyanate compounds synthesize an adduct of a compound having two active hydrogen groups in the molecule and a bifunctional isocyanate compound (prepolymer; “(PP)” in the following synthesis scheme). Thereafter, this prepolymer can also be obtained by reacting a compound having three or more active hydrogen groups in the molecule (the following synthesis scheme 2).

--Synthetic scheme 2--

  Examples of the bifunctional isocyanate compound include a bifunctional aromatic isocyanate compound and a bifunctional aliphatic isocyanate compound.

Specific examples of the bifunctional isocyanate compound include isophorone diisocyanate (IPDI), m-phenylene diisocyanate, p-phenylene diisocyanate, 2,6-tolylene diisocyanate, 2,4-tolylene diisocyanate (TDI), naphthalene-1, 4-diisocyanate, diphenylmethane-4,4′-diisocyanate (MDI), 3,3′-dimethoxy-biphenyl diisocyanate, 3,3′-dimethyldiphenylmethane-4,4′-diisocyanate, m-xylylene diisocyanate (XDI), p-xylylene diisocyanate, 4-chloroxylylene-1,3-diisocyanate, 2-methylxylylene-1,3-diisocyanate, 4,4′-diphenylpropane diisocyanate, 4,4′-diphenylhe Safluoropropane diisocyanate, trimethylene diisocyanate, hexamethylene diisocyanate (HDI), propylene-1,2-diisocyanate, butylene-1,2-diisocyanate, cyclohexylene-1,2-diisocyanate, cyclohexylene-1,3-diisocyanate, Cyclohexylene-1,4-diisocyanate, dicyclohexylmethane-4,4′-diisocyanate, 1,4-bis (isocyanatemethyl) cyclohexane, 1,3-bis (isocyanatemethyl) cyclohexane (HXDI), norbornene diisocyanate (NBDI), Trimethylhexamethylene diisocyanate (TMHDI), lysine diisocyanate, 1,3-bis (2-isocyanato-2-propyl) benzene, etc. It is.
Among these bifunctional isocyanate compounds, compounds having structures shown in the following (I-1) to (I-24) are preferable.

  Among these difunctional isocyanate compounds, isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), trimethylhexamethylene diisocyanate (TMHDI), 1,3-bis (isocyanatomethyl) cyclohexane (HXDI), m-xylylene diisocyanate (XDI) and at least one selected from dicyclohexylmethane-4,4′-diisocyanate (HMDI) are preferred.

  Moreover, as a bifunctional isocyanate compound, the bifunctional isocyanate compound induced | guided | derived from said compound can also be used. For example, Duranate (registered trademark) D101, D201, A101 (manufactured by Asahi Kasei Corporation) and the like can be mentioned.

  The compound having three or more active hydrogen groups in the molecule is a compound having three or more groups in the molecule selected from a hydroxy group, a primary amino group, a secondary amino group, and a mercapto group. For example, the compound of the structure represented by the following (H-1)-(H-13) is mentioned. In addition, n in the compounds (H-4), (H-5), and (H-11) represents an integer selected from 1 to 100, for example.

As the adduct type trifunctional or higher functional isocyanate compound, a commercially available product may be used.
Examples of commercially available products include Takenate (registered trademark) D-102, D-103, D-103H, D-103M2, P49-75S, D-110, D-120N, D-140N, D-160N (Mitsui Chemicals). Co., Ltd.), Death Module (registered trademark) L75, UL57SP (manufactured by Sumika Bayer Urethane Co., Ltd.), Coronate (registered trademark) HL, HX, L (manufactured by Nippon Polyurethane Co., Ltd.), P301-75E (manufactured by Asahi Kasei Corporation) ) And the like.

  Among these adduct-type trifunctional or higher functional isocyanate compounds, at least one selected from D-110, D-120N, D-140N, and D-160N (manufactured by Mitsui Chemicals, Inc.) is more preferable.

-Biuret type or isocyanurate type-
The isocyanurate type trifunctional or higher functional isocyanate compound is preferably a compound represented by the following formula (11C).
The biuret type trifunctional or higher functional isocyanate compound is preferably a compound represented by the following formula (11D).

In formula (11C) and formula (11D), R ¹ , R ² , and R ³ each independently represent a divalent organic group.
In formula (11C) and formula (11D), R ¹ , R ² , and R ³ each independently represent an alkylene group that may have a substituent having 1 to 20 carbon atoms, or 1 to 20 carbon atoms. A cycloalkylene group which may have a substituent or an arylene group which may have a substituent having 1 to 20 carbon atoms is preferable.
In formula (11C) and formula (11D), R ¹ , R ² , and R ³ are each independently a group selected from the groups represented by the above-described (R-1) to (R-20). It is particularly preferred.

In formula (11C) and formula (11D), R ^{1 to} R ³ are each independently a group derived from isophorone diisocyanate (IPDI) (R-3) or a group derived from hexamethylene diisocyanate (HDI). (R-7), a group derived from trimethylhexamethylene diisocyanate (TMHDI) (R-5), a group derived from m-xylylene diisocyanate (XDI) (R-9), 1,3-bis (isocyanate) More preferably, it is either a group (R-1) derived from (methyl) cyclohexane or a group (R-2) derived from dicyclohexylmethane 4,4′-diisocyanate.

As the biuret type trifunctional or higher functional isocyanate compound, a commercially available product may be used. Examples of commercially available products include Takenate (registered trademark) D-165N, NP1100 (manufactured by Mitsui Chemicals), Death Module (registered trademark) N3200 (Suika Bayer Urethane), Duranate (registered trademark) 24A-100 (Asahi Kasei Corporation) Company-made).
As the isocyanurate-type trifunctional or higher functional isocyanate compound, commercially available products may be used. Examples of commercially available products include Takenate (registered trademark) D-127, D-170N, D-170HN, D-172N, D-177N (manufactured by Mitsui Chemicals), Sumijour N3300, Death Module (registered trademark) N3600. , N3900, Z4470BA (Sumika Bayer Urethane), Coronate (registered trademark) HX, HK (manufactured by Nippon Polyurethane Co., Ltd.), Duranate (registered trademark) TPA-100, TKA-100, TSA-100, TSS-100, TLA- 100, TSE-100 (manufactured by Asahi Kasei Corporation) and the like.

  Among these biuret type and isocyanurate type trifunctional or higher functional isocyanate compounds, DURANATE (registered trademark) 24A-100 (manufactured by Asahi Kasei Corporation), D-120N, D-127 (manufactured by Mitsui Chemicals, Inc.), TKA- 100, TSS-100, and TSE-100 (manufactured by Asahi Kasei Corporation) are more preferable.

(Water or a compound having two or more active hydrogen groups)
The shell of the microcapsule can be formed by reacting the above-described trifunctional or higher functional isocyanate compound with water or a compound having two or more active hydrogen groups.
As a compound to be reacted with a trifunctional or higher functional isocyanate compound, water can be generally used. By reacting a trifunctional or higher functional isocyanate compound with water, a three-dimensional crosslinked structure having a urea bond is formed.
Moreover, as a compound made to react with a trifunctional or more than trifunctional isocyanate compound, the compound which has two or more active hydrogen groups besides water is also mentioned. Examples of the compound having two or more active hydrogen groups include a compound having a hydroxy group (—OH), an amino group (—NH), and a thiol group (—SH) in the molecule. Specifically, polyfunctional alcohol, polyfunctional phenol, polyfunctional amine having a hydrogen atom on a nitrogen atom, polyfunctional thiol, and the like can be used.
By reacting a trifunctional or higher functional isocyanate compound with a polyfunctional alcohol or polyfunctional phenol, a three-dimensional crosslinked structure having a urethane bond is formed.
By reacting a trifunctional or higher functional isocyanate compound with a polyfunctional amine having a hydrogen atom on a nitrogen atom, a three-dimensional crosslinked structure having a urea bond is formed.

Specific examples of the polyfunctional alcohol include propylene glycol, glycerin, trimethylolpropane, 4,4 ′, 4 ″ -trihydroxytriphenylmethane, and the like.
Specific examples of the polyfunctional amine include diethylenetriamine, tetraethylenepentamine, and lysine.
Specific examples of the polyfunctional thiol include 1,3-propanedithiol and 1,2-ethanedithiol.
Specific examples of the polyfunctional phenol include bisphenol A.
These compounds may be used individually by 1 type, and may use 2 or more types together.

  The compound having two or more active hydrogen groups includes a compound having three or more active hydrogen groups in the aforementioned molecule.

-Hydrophilic group that the shell may have-
The shell of the microcapsule preferably has at least one hydrophilic group.
When the shell has a hydrophilic group, dispersibility in an aqueous medium is further improved. Therefore, if the microcapsule is used for ink, the dischargeability and dispersibility stability of the ink composition can be further improved.
Further, when the microcapsule has a hydrophilic group in the shell, the hydrophilicity of the microcapsule is improved and the redispersibility is excellent.
In the shell, hydrophilic groups are present as part of the three-dimensional crosslinked structure.
Here, “the hydrophilic group exists as a part of the three-dimensional crosslinked structure” means that the hydrophilic group is covalently bonded to a portion other than the hydrophilic group of the three-dimensional crosslinked structure.
The covalent bond between the hydrophilic group and a portion other than the hydrophilic group of the three-dimensional cross-linked structure is preferably a urethane bond or a urea bond, and more preferably a urea bond.

Examples of the hydrophilic group that may be present in the shell include an anionic group and a nonionic group. More specifically, carboxylic acid group, carboxylic acid group salt, phosphonic acid group, phosphonic acid group salt, phosphoric ester group, phosphoric ester group salt, phosphoric acid group, phosphoric acid group salt, sulfonic acid Groups, sulfonic acid group salts, sulfuric acid groups, sulfuric acid group salts, groups having a polyether structure (eg, polyethylene oxide, polypropylene oxide, etc.), groups having a betaine structure, ammonium groups, sulfonium groups, phosphonium groups, and the like. It is done. In the present specification, the “hydrophilic group” is distinguished from the above-described active hydrogen groups (hydroxy group, primary amino group, secondary amino group, and mercapto group). The above-mentioned carboxylic acid group salts, sulfonic acid group salts, sulfuric acid group salts, phosphonic acid group salts, and phosphoric acid group salts are salts formed by neutralization in the manufacturing process of microcapsules. Also good. The shell of the microcapsule may have only one kind of hydrophilic group or two or more kinds.
The hydrophilic group that can be introduced into the shell is preferably at least one selected from a group having a polyether structure, a carboxylic acid group, and a salt of the carboxylic acid group.

A method for introducing a hydrophilic group into the shell of the microcapsule will be described.
The introduction of the hydrophilic group into the shell is performed by reacting the above-described trifunctional or higher isocyanate compound with water or a compound having two or more active hydrogen groups and a compound having a hydrophilic group. Can do.
In addition, the introduction of the hydrophilic group into the shell of the microcapsule first produces an isocyanate compound into which a hydrophilic group has been introduced by reacting a bifunctional isocyanate compound with a compound having a hydrophilic group. By reacting this “isocyanate compound having a hydrophilic group introduced” with a compound having two or more active hydrogen groups, a trifunctional or higher functional isocyanate compound having a hydrophilic group introduced is produced. It can also be carried out by reacting “a trifunctional or higher functional isocyanate compound into which a hydrophilic group is introduced” and a compound having water or two or more active hydrogen groups.

-Compound having a hydrophilic group-
Examples of the compound having a hydrophilic group include α-amino acids (specifically, lysine, alanine, arginine, asparagine, aspartic acid, cysteine, glutamine, glutamic acid, glycine, histidine, isoleucine, leucine, methionine, phenylalanine, proline, serine. , Threonine, tryptophan, tyrosine, valine) and the like. Examples of the compound having a hydrophilic group include the following specific examples in addition to the α-amino acid.

  When a compound having an anionic group is used as the compound having a hydrophilic group, the compound having an anionic group is an inorganic base such as sodium hydroxide or potassium hydroxide; an organic base such as triethylamine; You may neutralize and use at least one part.

Of the compounds having a hydrophilic group, the compound having a nonionic group is preferably a compound having a polyether structure, more preferably a compound having a polyoxyalkylene chain.
Specific examples of the compound having a polyoxyalkylene chain include polyethylene oxide, polypropylene oxide, polytetramethylene oxide, polystyrene oxide, polycyclohexylene oxide, polyethylene oxide-polypropylene oxide-block copolymer, polyethylene oxide-polypropylene oxide random copolymer. A polymer etc. are mentioned.
Among these compounds having a polyoxyalkylene chain, polyethylene oxide, polypropylene oxide, and polyethylene oxide-polypropylene oxide block copolymers are preferable, and polyethylene oxide is more preferable.
Examples of the compound having a polyether structure include polyethylene oxide monoethers (monoethers include, for example, monomethyl ether and monoethyl ether), polyethylene oxide monoesters (monoesters include, for example, , Monoacetic acid ester, mono (meth) acrylic acid ester and the like) are also preferable.

--Isocyanate compound having a hydrophilic group introduced--
Further, as described above, an isocyanate compound into which a hydrophilic group has been introduced can also be used for introducing a hydrophilic group into the shell.
Examples of the isocyanate compound having a hydrophilic group introduced include a compound having a hydrophilic group, isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), trimethylhexamethylene diisocyanate (TMHDI), and 1,3-bis (isocyanatomethyl) cyclohexane. A reaction product with (HXDI), m-xylylene diisocyanate (XDI), or dicyclohexylmethane-4,4′-diisocyanate (HMDI) is preferred.

  When a group having a polyether structure is introduced into the shell, an adduct of trimethylolpropane (TMP), m-xylylene diisocyanate (XDI), and polyethylene glycol monomethyl ether as an isocyanate compound into which a hydrophilic group has been introduced ( For example, it is preferable to use Mitsui Chemicals' Takenate D-116N.

In addition, when a carboxy group or a salt thereof is introduced into the shell, 2,2-bis (hydroxymethyl) propionic acid (DMPA) or a salt thereof and isophorone diisocyanate (IPDI) are used as an isocyanate compound into which a hydrophilic group is introduced. And a reaction product (that is, an isocyanate compound containing a carboxy group or a salt thereof) is preferably used.
The salt of the carboxy group is preferably a sodium salt, potassium salt, triethylamine salt or dimethylethanolamine salt, more preferably a sodium salt or triethylamine salt.

  When a compound having a hydrophilic group is used for introducing a hydrophilic group into the shell, the amount of the compound having a hydrophilic group is preferably 0.1% by mass to 50% by mass with respect to the total solid content of the microcapsule. 0.1 mass% to 45 mass% is more preferable, 0.1 mass% to 40 mass% is still more preferable, 1 mass% to 35 mass% is still more preferable, and 3 mass% to 30 mass% is still more preferable.

-Polymerizable group that the shell may have-
The microcapsule has a polymerizable group (that is, a compound having a polymerizable group) in the core, and thus has a polymerizable group. In addition to the polymerizable group of the polymerizable compound contained in the core, the microcapsule shell has And may have a polymerizable group.
When the shell of the microcapsule has a polymerizable group, the adjacent microcapsules are bonded to each other by irradiation with active energy rays, and an image having better film strength can be formed.

A method for introducing a polymerizable group into the shell of the microcapsule will be described.
As a method for introducing a polymerizable group into the shell of a microcapsule, for example, when forming a three-dimensional cross-linked structure having at least one kind of bond selected from a urethane bond and a urea bond, the above-described trifunctional or higher functional isocyanate is used. A method of reacting a compound, water or a compound having two or more active hydrogen groups as described above, and a monomer for introducing a polymerizable group;
When producing the above-described trifunctional or higher functional isocyanate compound, first, the aforementioned bifunctional isocyanate compound and the polymerizable group-introducing monomer are reacted to produce an isocyanate compound having a polymerizable group introduced, and then , A method of reacting an isocyanate compound having this polymerizable group introduced with water or a compound having two or more active hydrogen groups as described above;
A method in which when the microcapsule is produced, the polymerizable group-introducing monomer is dissolved in the oil phase component together with the components constituting the microcapsule, and the oil phase component and the aqueous phase component are mixed and emulsified and dispersed;
Etc.

Examples of the polymerizable compound used for introducing the polymerizable group into the microcapsule include a compound having at least one active hydrogen group and at least one terminal having an ethylenically unsaturated bond.
A compound having at least one active hydrogen group and at least one terminal having an ethylenically unsaturated bond can be represented by the following structural formula (a).
L ¹ Lc _m Z _n formula (a)

In Structural Formula (a), L ¹ represents an m + n-valent linking group, m and n are each independently an integer selected from 1 to 100, and Lc represents a monovalent ethylenically unsaturated group. , Z represents an active hydrogen group.
L ¹ is a divalent or higher aliphatic group, a divalent or higher aromatic group, a divalent or higher heterocyclic group, —O—, —S—, —NH—, —N <, —CO—, —SO. -, - SO ₂ - or preferably a combination thereof.
m and n are each independently preferably 1 to 50, more preferably 2 to 20, still more preferably 3 to 10, and particularly preferably 3 to 5.
Examples of the monovalent ethylenically unsaturated group represented by Lc include an allyl group, a vinyl group, an acryloyl group, and a methacryloyl group.
Z is preferably OH, SH, NH or NH ₂ , more preferably OH or NH ₂ , and still more preferably OH.

  Examples of compounds having at least one active hydrogen group and having an ethylenically unsaturated bond at at least one terminal are shown below, but are not limited to this structure. In addition, n in the compounds (a-3) and (a-14) represents an integer selected from 1 to 90, for example.

  As the compound having at least one active hydrogen group and having at least one ethylenically unsaturated bond, a commercially available product may be used. For example, hydroxyethyl acrylate (Osaka Organic Chemical Co., Ltd.) Manufactured), 4-hydroxybutyl acrylate, 1,4-cyclohexanedimethanol monoacrylate (manufactured by Nippon Kasei Co., Ltd.), BLEMMER (registered trademark) AE-90U (n = 2), AE-200 (n = 4.5) AE-400 (n = 10), AP-150 (n = 3), AP-400 (n = 6), AP-550 (n = 9), AP-800 (n = 13) (NOF Corporation) Manufactured), DENACOL (registered trademark) ACRYLATE DA-212, DA-250, DA-314, DA-721, DA-722, DA-911M, DA-920 Acrylates such as DA-931 (manufactured by Nagase ChemteX Corporation), 2-hydroxyethyl methacrylate (manufactured by Kyoeisha Chemical Co., Ltd.), Bremer (registered trademark) PE-90 (n = 2), PE-200 (n = 4. 5), PE-350 (n = 8), PP-1000 (N = 4-6), PP-500 (n = 9), PP-800 (n = 13) (manufactured by NOF Corporation), A- Examples thereof include methacrylates such as TMM-3L (manufactured by Shin-Nakamura Chemical Co., Ltd.) and SR399E (manufactured by SARTOMER), and acrylamide (manufactured by KJ Chemicals Co., Ltd.).

  Among these compounds having at least one active hydrogen group and at least one terminal having an ethylenically unsaturated bond, hydroxyethyl acrylate (manufactured by Osaka Organic Chemical Co., Ltd.), AE-400 (n = 10) AP-400 (n = 6) (manufactured by NOF Corporation), DENACOL (registered trademark) ACRYLATE DA-212 (manufactured by Nagase ChemteX Corporation), and PP-500 (n = 9) (manufactured by NOF Corporation) ), A-TMM-3L (manufactured by Shin-Nakamura Chemical Co., Ltd.) and SR399E (manufactured by SARTOMER) are preferable.

  For example, as shown in the following synthesis scheme 3, the introduction of the polymerizable group into the microcapsule has an isocyanate group of a trifunctional or higher functional isocyanate compound and at least one active hydrogen group, and at least one terminal is ethylenic. An isocyanate compound having a polymerizable group introduced by reacting with an active hydrogen group of a compound having an unsaturated bond is prepared, and the prepared isocyanate compound having an introduced polymerizable group and two or more active hydrogens described above This can be carried out by reacting a group-containing compound.

-Synthetic scheme 3-

In Synthesis Scheme 3, X and n have the same meanings as X and n in formula (I), X ₁ represents a divalent linking group, R represents a hydrogen atom or a methyl group, and Z represents an oxygen atom (O). Or represents a nitrogen atom (N).

  The polymerizable group-introducing monomer may be a single monomer or a combination of two or more monomers.

In the production of an isocyanate compound into which a polymerizable group is introduced, a polyisocyanate (that is, a trifunctional or higher functional isocyanate compound) and a polymerizable group-introducing monomer are mixed with the number of moles of active hydrogen groups in the polymerizable group-introducing monomer. The reaction may be performed at a ratio of 0.01 to 0.3 times the number of moles of isocyanate groups (more preferably 0.02 to 0.25 times, still more preferably 0.03 to 0.2 times). preferable.
The isocyanate compound having a polymerizable group introduced may have an average number of functional groups of 3 or less in the isocyanate group. However, even in this case, it is possible to form a shell having a three-dimensional crosslinked structure if at least one trifunctional or higher functional isocyanate compound is contained in the raw material for forming the shell.

~ Physical properties of microcapsules ~
The volume average particle size of the microcapsules is preferably 0.01 μm to 10.0 μm, more preferably 0.01 μm to 5 μm, more preferably 0.05 μm from the viewpoint of dispersibility when applied to the ink composition. More preferably, it is ˜1 μm.
The volume average particle diameter of the microcapsules can be measured by a light scattering method. In addition, the value measured by the wet particle size distribution measuring device LA-960 (made by Horiba Ltd.) is used for the volume average particle diameter in this specification.

From the viewpoint of dispersibility and ease of film formation, the microcapsules are preferably contained in an amount of 1% by mass to 50% by mass with respect to the total mass of the ink composition, and 3% by mass. The content is more preferably ˜40% by mass, and further preferably 5% by mass to 30% by mass.
The content of the microcapsule is a value including a polymerizable compound contained in the core of the microcapsule and solid components such as a photopolymerization initiator and a sensitizer that can be contained in the core.
The total solid content of the microcapsule is preferably 50% by mass or more, more preferably 60% by mass or more, further preferably 70% by mass or more, and further preferably 80% by mass or more with respect to the total solid content of the ink composition. The upper limit of the total solid content of the microcapsule is preferably 99% by mass or less, and more preferably 95% by mass or less with respect to the total solid content of the ink composition.
The “total solid content” of the ink composition refers to the total amount of the ink composition excluding the dispersion medium (such as water and a high-boiling solvent).

~ Formation of microcapsules ~
The method for producing the microcapsules is not particularly limited.
As a manufacturing method of a microcapsule, the manufacturing method of embodiment described below is preferable from a viewpoint that the above-mentioned microcapsule is easy to be obtained.

In one embodiment of the method for producing a microcapsule, an oil phase component containing a trifunctional or higher functional isocyanate compound, a polymerizable compound, and an organic solvent and an aqueous phase component containing water are mixed and emulsified and dispersed. A method having a preparation step of preparing an aqueous dispersion of capsules is preferred.
In the preparation step, it is preferable that the oil phase component further contains a photopolymerization initiator, a compound having a hydrophilic group in at least one of the oil phase component and the water phase component.

-Preparation process-
In the preparation step, an oil phase component containing a tri- or higher functional isocyanate compound, a polymerizable compound, and an organic solvent and an aqueous phase component containing water are mixed and emulsified and dispersed to prepare an aqueous dispersion of microcapsules. It is preferable that it is a process.
In the preparation step, it is preferable that the oil phase component further contains a photopolymerization initiator, a compound having a hydrophilic group in at least one of the oil phase component and the water phase component.
By mixing and emulsifying and dispersing the oil phase component and the aqueous phase component as described above, the aforementioned microcapsules are formed.
Here, an embodiment will be described in which a photopolymerization initiator is further contained as the oil phase component and a compound having a hydrophilic group is contained as the water phase component.

The oil phase component used in the preparation step includes a trifunctional or higher functional isocyanate compound, a polymerizable compound, a photopolymerization initiator, and an organic solvent.
The aqueous phase component used in the preparation step includes water and a compound having a hydrophilic group.
The preparation step includes a shell having a three-dimensional crosslinked structure including a hydrophilic group and at least one bond selected from a urethane bond and a urea bond, a polymerizable compound encapsulated in the shell, and a photopolymerization initiator. And a microcapsule including the core. The formed microcapsules become a dispersoid in the produced aqueous dispersion.
On the other hand, water in the aqueous phase component serves as a dispersion medium in the produced aqueous dispersion.

More specifically, the shell having a three-dimensional crosslinked structure containing a urea bond is formed by the reaction of a trifunctional or higher functional isocyanate compound with water. Moreover, when a trifunctional or higher functional isocyanate compound contains a urethane bond (for example, in the case of a trifunctional or higher functional isocyanate compound using a polyfunctional alcohol as a raw material), the three-dimensional crosslinked structure of the shell contains a urethane bond. Become.
Further, a neutralizing agent may be added to the aqueous phase, and the hydrophilic group of the compound having a hydrophilic group may be neutralized with the neutralizing agent. Since a compound having a hydrophilic group is also involved in the shell formation reaction, when the hydrophilic group is neutralized, the hydrophilic group neutralized to the three-dimensional crosslinked structure of the shell (for example, the hydrophilic group is an acid group). If so, a salt of an acid group) is introduced. The introduced hydrophilic group salt is excellent in the effect of dispersing the microcapsules in water. In addition, the neutralization degree of a hydrophilic group can be adjusted with the quantity etc. of a neutralizing agent.

  Examples of the neutralizing agent include sodium hydroxide, potassium hydroxide, triethanolamine and the like.

  When the oil phase component contains an isocyanate compound having a polymerizable group, the isocyanate compound having a polymerizable group also participates in the shell formation reaction, and therefore, a polymerizable group is introduced into the shell (that is, polymerizable). A shell having a group is formed).

Examples of the organic solvent contained in the oil phase component include ethyl acetate and methyl ethyl ketone.
It is preferable that at least a part of the organic solvent is removed in the process of forming the microcapsules and after the formation of the microcapsules.

The details of the trifunctional or higher functional isocyanate compound contained in the oil phase component are as described above.
The details of the isocyanate compound having a polymerizable group and the polymerizable compound contained in the oil phase component are as described above.
The details of the photopolymerization initiator contained in the oil phase component are as described above.

The oil phase component may contain other components as necessary in addition to the above-described components.
Examples of the other components include the sensitizer described above.
By including a sensitizer in the oil phase component, these can be included in the core of the microcapsule.

The details of the compound having a hydrophilic group contained in the aqueous phase component are as described above.
The aqueous phase component may contain other components in addition to the above-described components as necessary.
Examples of other components include surfactants described later.

The total amount obtained by removing the organic solvent and water from the oil phase component and the aqueous phase component in the aforementioned method corresponds to the total solid content of the microcapsules to be produced.
The content of the polymerizable compound in the oil phase component is preferably 30% by mass to 75% by mass, more preferably 35% by mass to 65% by mass, and further 35% by mass to 60% by mass with respect to the solid content. preferable.
The content of the photopolymerization initiator in the oil phase component is preferably 0.1% by mass to 25% by mass, more preferably 0.5% by mass to 20% by mass, and 0.5% by mass with respect to the solid content. % To 15% by mass is more preferable.
The ratio of the photopolymerization initiator to the polymerizable compound is preferably 0.5% by mass to 25% by mass, more preferably 1% by mass to 20% by mass, and still more preferably 5% by mass to 10% by mass on a mass basis.
The amount of the trifunctional or higher functional isocyanate compound in the oil phase component is not particularly limited. For example, it is preferably 5% by mass to 50% by mass with respect to the total solid content, and 10% by mass to 40% by mass. Is more preferable, and 15 mass%-30 mass% is still more preferable.
When the oil phase component contains an isocyanate compound having polymerizability, the amount of the polymerizable compound in the oil phase component is not particularly limited, for example, 0.1% by mass to 50% by mass with respect to the total solid content. It is preferable that
The amount of the organic solvent is not particularly limited, and is appropriately set depending on the type and amount of the components contained in the oil phase component.

The amount of the compound having a hydrophilic group in the aqueous phase component is not particularly limited, and is preferably 0.01% by mass to 1% by mass with respect to the total solid content, for example.
The amount of the neutralizing agent in the aqueous phase component is not particularly limited as long as the neutralization degree of the hydrophilic group can be a desired value, and the type of the compound having a hydrophilic group contained in the aqueous phase component, It is set appropriately depending on the amount and the like.
The amount of water is not particularly limited, and is appropriately selected depending on the type and amount of components contained in the oil phase component.

Each component contained in the oil phase component may be simply mixed, all the components may be mixed at once, or each component may be divided into several parts and mixed.
As in the case of the oil phase component, each component contained in the aqueous phase component may be simply mixed. Also good.
The method for mixing the oil phase component and the aqueous phase component is not particularly limited, and examples thereof include mixing by stirring.

The method for emulsifying the mixture obtained by mixing is not particularly limited, and examples thereof include emulsification using an emulsifier such as a homogenizer (for example, a disperser).
The rotation speed of the disperser in the emulsification is, for example, 5000 rpm to 20000 rpm, and preferably 10,000 rpm to 15,000 rpm.
The rotation time in emulsification is, for example, 1 minute to 120 minutes, preferably 3 minutes to 60 minutes, more preferably 3 minutes to 30 minutes, and further preferably 5 minutes to 15 minutes.

The emulsification in the preparation step may be performed under heating.
By performing the emulsification under heating, the formation reaction of microcapsules by the emulsification can be advanced more efficiently. Further, by performing emulsification under heating, it is easy to remove at least a part of the organic solvent contained as the oil phase component from the mixture.
The heating temperature (that is, the reaction temperature) when emulsification is performed under heating is preferably 35 ° C to 70 ° C, and more preferably 40 ° C to 60 ° C.

The preparation process also includes an emulsification step for emulsifying the mixture (for example, at a temperature of less than 35 ° C.) and a heating step for heating the emulsion obtained in the emulsification step (for example, at a temperature of 35 ° C. or higher). May be.
According to an embodiment in which the preparation process includes an emulsification stage and a heating stage, a shell having a stronger three-dimensional cross-linked structure is formed, so that an aqueous dispersion capable of forming a film with higher hardness can be produced. .
In an embodiment in which the preparation process includes an emulsification stage and a heating stage, preferred ranges of the heating temperature and heating time in the heating stage are the same as the preferred ranges of the heating temperature and heating time when emulsification is performed under heating, respectively.

In addition to the manufacturing method of the above-described embodiment (hereinafter, also referred to as “the manufacturing method of the first embodiment”), for example, a microcapsule aqueous dispersion is manufactured by the following methods (2) to (4): Can do.
(2) A trifunctional or higher functional isocyanate compound, a polymerizable compound, a photopolymerization initiator, a compound having a hydrophilic group, a neutralizer and an oil phase component containing an organic solvent, and an aqueous phase component containing water are mixed. Manufacturing method having a preparation step of emulsifying and dispersing to prepare an aqueous dispersion (hereinafter also referred to as “manufacturing method of the second embodiment”),
(3) A trifunctional or higher functional isocyanate compound, a polymerizable compound, a photopolymerization initiator, a compound having a hydrophilic group, and an oil phase component containing an organic solvent and an aqueous phase component containing water and a neutralizing agent are mixed. And a production method (hereinafter also referred to as “production method of the third embodiment”) having a preparation step of emulsifying and dispersing to prepare an aqueous dispersion, and (4) a trifunctional or higher functional isocyanate compound, a polymerizable compound, Preparation to prepare an aqueous dispersion by mixing and emulsifying and dispersing an oil phase component containing a photopolymerization initiator, a neutralizing agent, and an organic solvent, and an aqueous phase component containing water and a compound having a hydrophilic group. The manufacturing method which has a process (henceforth "the manufacturing method of 4th Embodiment") is mentioned.

  In any of the manufacturing methods of the second to fourth embodiments, in the preparation step, an oil phase component and an aqueous phase component were mixed and obtained in the same manner as in the manufacturing method of the first embodiment. By emulsifying and dispersing the mixture, a shell having a three-dimensional cross-linking structure including a hydrophilic group and at least one bond selected from a urethane bond and a urea bond, a polymerizable compound encapsulated in the shell, and photopolymerization A microcapsule having a core containing an initiator is formed. The formed microcapsules become a dispersoid in the produced water dispersion, and water in the aqueous phase component becomes a dispersion medium in the produced water dispersion.

In the production methods of the second and third embodiments, the amount of the compound having a hydrophilic group in the oil phase component is not particularly limited, and is, for example, 0.01% by mass to 1% with respect to the total solid content. It is preferable that it is mass%.
In the production method of the fourth embodiment, the amount of the compound having a hydrophilic group in the aqueous phase component is not particularly limited, and is, for example, 0.01% by mass to 1% by mass with respect to the total solid content. Preferably there is.
In the production methods of the second and fourth embodiments, the amount of the neutralizing agent in the oil phase component is not particularly limited as long as the neutralization degree of the hydrophilic group can be set to a desired value. It is appropriately set depending on the type, amount, etc. of the compound having a hydrophilic group contained in the middle or aqueous phase component. In the manufacturing method of 3rd Embodiment, it is the same also about the quantity of the neutralizing agent in an aqueous phase component.

-Other processes-
The manufacturing method of the microcapsule of the said embodiment may have other processes other than a preparation process as needed.
Examples of other steps include a step of adding other components.
The other components to be added include those described later as other components that can be contained in the ink composition.

(water)
The ink composition contains water.
There is no restriction | limiting in particular in the quantity of water, It is 30 mass%-99 mass%, More preferably, it is 40 mass%-95 mass%, More preferably, it is 50 mass%-90 mass%.

(Photopolymerization initiator that can be contained outside the microcapsule)
The ink composition may contain a photopolymerization initiator outside the microcapsule.
When the ink composition contains a photopolymerization initiator outside the microcapsules, the efficiency of the polymerization reaction between the microcapsules can be improved, and a film having higher film strength can be formed. Furthermore, when the active energy ray (light) is irradiated to the ink composition, the polymerization reaction is highly efficient even for the active energy ray (light) having a low exposure illuminance (for example, 40 mJ / cm ^{2 to} 70 mJ / cm ² ). proceed.

Examples of the photopolymerization initiator that can be contained outside the microcapsule include the same photopolymerization initiator as described above (that is, the photopolymerization initiator that can be included in the microcapsule).
The photopolymerization initiator that can be contained outside the microcapsule is preferably a water-soluble or water-dispersible photopolymerization initiator. From this viewpoint, for example, DAROCUR (registered trademark) 1173, IRGACURE (registered trademark) 2959, IRGACURE (registered trademark) 754, DAROCUR (registered trademark) MBF, IRGACURE (registered trademark) 819DW, IRGACURE (registered trademark) 500 (manufactured by BASF), acyl phosphine oxide described in International Publication No. 2014/095724 Compounds, and photopolymerization initiators described in International Publication No. 86/05778.
Note that “water-soluble” means a property in which the amount dissolved in 100 g of distilled water at 25 ° C. exceeds 1 g when dried at 105 ° C. for 2 hours.
“Water dispersibility” refers to the property of being insoluble in water and being dispersed in water. Here, “water-insoluble” means a property in which the amount dissolved in 100 g of distilled water at 25 ° C. is 1 g or less when dried at 105 ° C. for 2 hours.

(Sensitizer that can be contained outside the microcapsule)
The ink composition may contain a sensitizer outside the microcapsule.
When the ink composition contains a sensitizer outside the microcapsule, the decomposition of the photopolymerization initiator by active energy ray irradiation can be further promoted.

  Examples of the sensitizer that can be contained outside the microcapsule include the same sensitizers as described above (that is, the sensitizer that can be included in the microcapsules).

(Other additives)
If necessary, other components other than those described above can be added to the ink composition. Hereinafter, other components will be described.

-Surfactant-
The ink composition may contain a surfactant. The surfactant used in the ink composition is distinguished from the surfactant used in manufacturing the microcapsules.
Examples of the surfactant include a nonionic surfactant, a cationic surfactant, and an anionic surfactant, and any surfactant may be used. However, the content of the anionic surfactant with respect to the total mass of the ink composition is preferably 1% by mass or less.
When the content of the anionic surfactant in the ink composition is 1% by mass or less, aggregation of the colorant in the ink composition is suppressed, and the dischargeability of the ink composition is excellent. From the same viewpoint, the content of the anionic surfactant is preferably 0.5% by mass or less, more preferably 0.1% by mass or less, and still more preferably 0% by mass (that is, not contained).

Examples of the surfactant include higher fatty acid salts, alkyl sulfates, alkyl ester sulfates, alkyl sulfonates, alkyl benzene sulfonates, sulfosuccinates, naphthalene sulfonates, alkyl phosphates, polyoxyalkylene alkyl ethers. Examples thereof include phosphate, polyoxyalkylene alkylphenyl ether, polyoxyethylene polyoxypropylene glycol, glycerin ester, sorbitan ester, polyoxyethylene fatty acid amide, and amine oxide.
The surfactant is preferably an alkyl sulfate having an alkyl chain length of 8 to 18 from the viewpoint of the dispersibility of the microcapsules. Sodium dodecyl sulfate (SDS, alkyl chain length: 12) and sodium cetyl sulfate (SCS) , Alkyl chain length: at least one selected from 16), more preferably sodium cetyl sulfate (SCS).

Examples of other surfactants other than the above-described surfactants include those described in JP-A Nos. 62-173463 and 62-183457. Examples of other surfactants include nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, acetylene glycols, polyoxyethylene / polyoxypropylene block copolymers, and siloxanes. Can be mentioned.
Moreover, an organic fluoro compound is also mentioned as a surfactant.
The organic fluoro compound is preferably hydrophobic. Examples of the organic fluoro compound include a fluorine-based surfactant, an oily fluorine-based compound (for example, fluorine oil), and a solid fluorine compound resin (for example, tetrafluoroethylene resin). Column 8 to column 17), and those described in JP-A Nos. 62-135826.

-Polymerization inhibitor-
A polymerization inhibitor may be added from the viewpoint of enhancing the storage stability. Examples of the polymerization inhibitor include p-methoxyphenol, quinones such as hydroquinone and methoxybenzoquinone, phenothiazine, catechol, alkylphenols, alkylbisphenols, zinc dimethyldithiocarbamate, copper dimethyldithiocarbamate, copper dibutyldithiocarbamate, and salicylic acid. Examples thereof include copper, thiodipropionic acid esters, mercaptobenzimidazole, phosphites, and the like, and p-methoxyphenol, catechols, and quinones are preferable. Hydroquinone, benzoquinone, p-methoxyphenol, TEMPO, TEMPOL, and cupron Al, tris (N-nitroso-N-phenylhydroxylamine) aluminum salt, and the like are more preferable.

-UV absorber-
In the ink composition, an ultraviolet absorber may be used from the viewpoint of improving the weather resistance of the obtained image and preventing discoloration.
Examples of the ultraviolet absorber include known ultraviolet absorbers such as benzotriazole compounds, benzophenone compounds, triazine compounds, and benzoxazole compounds.

~ Preferable physical properties of ink composition ~
The ink composition preferably has a viscosity of 50 mPa · s or less, more preferably 3 mPa · s to 15 mPa · s, and more preferably 3 mPa · s to 13 mPa when the liquid temperature is 25 ° C. to 50 ° C. -More preferably, it is s. In particular, the viscosity of the liquid at 25 ° C. is preferably 50 mPa · s or less as the ink composition. When the viscosity of the liquid is in the above range, high ejection stability can be realized when applied to ink jet recording.
The viscosity of the ink composition is a value measured using a viscometer: VISCOMETER TV-22 (manufactured by Toki Sangyo Co., Ltd.).

[Base material]
The substrate is preferably a non-permeable substrate from the viewpoint that the effects of the ink jet recording method of the present disclosure appear more remarkably.
The “non-permeable” of the non-permeable substrate means that the water contained in the ink composition is little absorbed or not absorbed. Specifically, the amount of absorbed water is 0.3 g / m ² or less. A certain property.
The amount of water absorbed by the base material was maintained at 25 ° C. for 1 minute in a state where water was in contact with an area of 100 mm × 100 mm of the image recording surface of the non-permeable base material. Is obtained, and the amount of absorption per unit area is calculated.

As a base material, for example, a metal plate (for example, aluminum, zinc, copper, etc.), a plastic film (for example, polyvinyl chloride resin, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, nitric acid) Cellulose, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc.).
Especially, as a base material, a non-absorbable base material can be used conveniently. As the non-absorbing substrate, a plastic substrate such as polyvinyl chloride, polyethylene terephthalate, or polyethylene is preferable, a polyvinyl chloride resin substrate is more preferable, and a polyvinyl chloride resin sheet or film is still more preferable.
The inkjet recording method of the present disclosure may be used for image recording on a substrate other than a plastic substrate.
Examples of the substrate other than the plastic substrate include a textile substrate.
Examples of the material for the textile substrate include natural fibers such as cotton, silk, hemp, and wool; chemical fibers such as viscose rayon and reocell; synthetic fibers such as polyester, polyamide, and acrylic; natural fibers, chemical fibers, and synthetic fibers And a mixture of at least two selected from the group consisting of fibers.
As the textile substrate, the textile substrate described in paragraphs 0039 to 0042 of International Publication No. 2015/158592 may be used.

~ Discharge method ~
In the ink jet recording method, the ink jet recording apparatus used is not particularly limited, and a known ink jet recording apparatus capable of achieving a target resolution can be arbitrarily selected and used. That is, any known ink jet recording apparatus including a commercially available product can discharge the ink composition A and the ink composition B onto the substrate in the image forming method.
Examples of the ink jet recording apparatus include an apparatus including an ink supply system, a temperature sensor, and a heating unit.
The ink supply system includes, for example, an original tank containing the ink composition A and the ink composition B, a supply pipe, an ink supply tank immediately before the inkjet head, a filter, and a piezo-type inkjet head. The piezo-type inkjet head preferably has a multi-size dot of 1 pl to 100 pl, more preferably 8 pl to 30 pl, preferably 320 dpi (dot per inch) × 320 dpi to 4000 dpi × 4000 dpi (dot per inch), more preferably 400 dpi ×. Driving can be performed so that ejection can be performed at a resolution of 400 dpi to 1600 dpi × 1600 dpi, more preferably 720 dpi × 720 dpi. In addition, dpi represents the number of dots per 2.54 cm (1 inch).

In the ink application process, it is desirable that the ejected ink composition A and the ink composition B have a constant temperature. Therefore, the ink jet recording apparatus includes a means for stabilizing the temperature of the ink composition A and the ink composition B. It is preferable to provide. The parts to be kept at a constant temperature are all the piping systems and members from the ink tank (intermediate tank if there is an intermediate tank) to the nozzle ejection surface. That is, heat insulation and heating can be performed from the ink supply tank to the inkjet head portion.
The temperature control method is not particularly limited, but for example, it is preferable to provide a plurality of temperature sensors at each piping site and perform heating control according to the flow rates of ink composition A and ink composition B and the environmental temperature. The temperature sensor can be provided near the ink supply tank and the nozzle of the inkjet head. Moreover, it is preferable that the head unit to be heated is thermally shielded or insulated so that the apparatus main body is not affected by the temperature from the outside air. In order to shorten the printer start-up time required for heating or to reduce the loss of heat energy, it is preferable to insulate from other parts and reduce the heat capacity of the entire heating unit.

<Heating process>
The ink jet recording method includes a heating step of heating the ink composition A and the ink composition B discharged onto the base material.
In the heat drying step, the ink composition A and the ink composition B discharged onto the substrate are evaporated by the heating means, and the concentration of the high boiling point solvent in the ink composition A and the ink composition B is improved. Therefore, both the ink composition A and the ink composition B have a low zeta potential, the charge repulsion of the microcapsules dispersed by the charge repulsion on the surface becomes weak, and the microcapsules aggregate. As a result, since the ink composition A and the ink composition B are thickened, the ink composition A and the ink composition B are fixed to the substrate.
At this time, since the absorbance of the ink composition A and the ink composition B and the concentration of the high boiling point solvent satisfy the formulas (1) and (2), the microcapsules containing carbon black tend to be destroyed by heating. In the ink composition B, the microcapsules can be aggregated before the microcapsules are broken. Therefore, the ink composition B can be fixed while suppressing the change in the shape of the droplets on the base material of the ink composition B.

  The heating is not limited as long as water can be evaporated. For example, the ink composition may be heated by irradiating it with infrared rays, heated by applying warm air to the ink composition, or heated by placing the ink composition in a heated atmosphere, These may be combined. As a heating method, it is preferable to heat the ink composition by irradiating it with infrared rays from the viewpoint that the effects of the present disclosure appear more remarkably.

The heating means is not particularly limited, and for example, an infrared irradiation device (such as an infrared lamp), a heat drum, a warm air machine, a heat oven, a heat plate heating, or the like can be used.
Especially, it is preferable to use an infrared irradiation apparatus from a viewpoint from which the effect of this indication appears more notably.

  When using an infrared irradiation apparatus, the infrared peak wavelength is preferably, for example, 800 nm to 1400 nm, more preferably 800 nm to 1000 nm, and still more preferably 800 nm to 900 nm.

When using the infrared radiator, the illumination intensity on the exposed surface of infrared, for ^example, is preferably ^{10mJ / cm 2 ~2000mJ / cm 2} , more preferably ^{20mJ / cm 2 ~1000mJ / cm 2} .

  In the case of using an infrared irradiation device, the time from the ink landing until the infrared irradiation is preferably, for example, 0.01 seconds to 120 seconds, and more preferably 0.01 seconds to 60 seconds. .

The irradiation time of infrared rays is not particularly limited. Further, infrared irradiation may be performed once or a plurality of times.
The irradiation time of infrared rays is preferably 0.05 seconds or more and 10 seconds or less, more preferably 0.1 seconds or more and 5 seconds or less, and further preferably 0.15 seconds or more and 3 seconds or less.
When the infrared irradiation time is 0.05 seconds or more, the reproducibility of fine lines is improved. On the other hand, when the irradiation time is 10 seconds or less, the graininess is further improved.

  Examples of the infrared irradiation device include a halogen heater and a ceramic heater.

  The heating temperature in the heating step is preferably 40 ° C or higher, more preferably about 40 ° C to 150 ° C, and still more preferably about 40 ° C to 80 ° C. The drying or heating time can be appropriately set in consideration of the composition of the ink composition A and the ink composition B to be used and the printing speed.

In the heating step, it is preferable to heat the ink composition A and the ink composition B under the same conditions.
“Heating under the same conditions” means heating the ink composition A and the ink composition B without changing conditions such as the type of heat source, the heating temperature, and the scanning speed in the heating step. Point to.
By heating under the same conditions, it is not necessary to change the heat source in accordance with each ink composition, and the productivity of inkjet recording is further improved.
Further, the heating may be started simultaneously with respect to the ink composition A and the ink composition B, or may be started at different timings. It is preferable to start heating simultaneously from the viewpoint of the productivity of inkjet recording.

<Irradiation process>
The ink jet recording method preferably includes an irradiation step of irradiating the ink composition A and the ink composition B heated by the above-described heating step with light (active energy rays). The ink composition A and the ink composition B heated by the heating process mean the ink composition A and the ink composition B that have been subjected to the heating process, and the ink composition A and the ink composition B are heated. It may be in a state where the temperature has increased, or it may be in a state in which the temperature has decreased after a lapse of time after heating.
An irradiation process will not be limited if it is a process of irradiating the ink composition A and the ink composition B which passed through the heating process with an active energy ray.
By irradiating the ink composition A and the ink composition B with active energy rays, the polymerization reaction of the microcapsules in the ink composition A and the ink composition B proceeds, and the film strength of the image can be improved. It becomes.

  Examples of active energy rays that can be used in the irradiation step include ultraviolet rays (UV light), visible rays, and electron beams. Among these, ultraviolet rays (UV light) are preferable.

The peak wavelength of the active energy ray (light) is preferably 200 nm to 405 nm, more preferably 220 nm to 390 nm, for example, depending on the absorption characteristics of the sensitizer used as necessary. More preferably, it is -385 nm.
In addition, when not using a sensitizer and a photoinitiator together, it is preferable that it is 200 nm-310 nm, for example, and 200 nm-280 nm are more preferable.

Exposure surface illuminance when the active energy ray (light) is irradiated, for ^{example, 10mJ / cm 2 ~2000mJ / cm} 2, ^is preferably a suitably be irradiated with 20mJ / cm ² ~1000mJ / cm 2 .

As a source for generating active energy rays (light), a mercury lamp, a metal halide lamp, a UV fluorescent lamp, a gas laser, a solid laser, and the like are widely known.
Further, the replacement of the light source exemplified above with a semiconductor ultraviolet light emitting device is very useful both industrially and environmentally.
Among semiconductor ultraviolet light emitting devices, LED (Light Emitting Diode) (preferably UV-LED) and LD (Laser Diode) (preferably UV-LD) are small in size, long life, high efficiency, and low cost. Expected.
As the light source, a metal halide lamp, an ultra high pressure mercury lamp, a high pressure mercury lamp, a medium pressure mercury lamp, a low pressure mercury lamp, an LED, or a blue-violet laser is preferable.
Among these, when a sensitizer and a photopolymerization initiator are used in combination, an ultra-high pressure mercury lamp capable of irradiating light with a wavelength of 365 nm, 405 nm, or 436 nm, light irradiation with a wavelength of 365 nm, 405 nm, or 436 nm is possible. A high-pressure mercury lamp or an LED capable of irradiating light with a wavelength of 355 nm, 365 nm, 385 nm, 395 nm, or 405 nm is more preferable, and an LED capable of irradiating light with a wavelength of 355 nm, 365 nm, 385 nm, 395 nm, or 405 nm is most preferable.

  As the irradiation conditions and the basic irradiation method, the irradiation conditions and irradiation methods disclosed in JP-A-60-132767 can be similarly applied. Specifically, a light source is provided on both sides of the head unit including the ink composition ejection device, and the head unit and the light source are scanned by a so-called shuttle method, or another light source that is not driven and is not driven. A method performed by another light source is preferable.

  The irradiation with the active energy ray may be performed after a certain period of time after the ink composition has landed and heated. The time from heating to irradiation with the active energy ray is preferably from 0.01 seconds to 120 seconds, more preferably from 0.01 seconds to 60 seconds.

The irradiation time of the active energy ray is not particularly limited. Further, the irradiation of active energy may be performed once or a plurality of times.
The irradiation time of the active energy ray is preferably 0.05 seconds or more and 10 seconds or less, more preferably 0.1 seconds or more and 5 seconds or less, and further preferably 0.15 seconds or more and 3 seconds or less.
When the irradiation time is 0.05 seconds or more, the film strength of the image is improved. On the other hand, productivity is improved when the irradiation time is 10 seconds or less.

In the irradiation step, it is preferable to perform light irradiation on the ink composition A and the ink composition B under the same conditions.
“Irradiating light under the same conditions” refers to performing light irradiation on the ink composition A and the ink composition B without changing conditions such as the type of light source, the amount of light, and the irradiation speed in the irradiation process. .
By performing light irradiation under the same conditions, it is not necessary to change the light source in accordance with each ink composition, and the productivity of inkjet recording is further improved.
Moreover, the light irradiation with respect to the ink composition A and the ink composition B may be performed simultaneously, may be performed continuously, and may be performed separately. From the viewpoint of inkjet recording productivity, it is preferable to perform light irradiation simultaneously or continuously.

<< Inkjet recording method using four-color ink composition >>
The inkjet recording method of the present disclosure described above may record an image using four color ink compositions.
In this case, the ink jet recording method includes the ink composition A1 including at least a polymerizable compound, the ink composition A1 including a microcapsule including at least a polymerizable compound, a high boiling point solvent, water, and a copper phthalocyanine pigment. Of the ink composition A2 containing a microcapsule, a high-boiling solvent, water, and a quinacridone pigment, and an ink composition A3 containing a microcapsule containing at least a polymerizable compound, a high-boiling solvent, water, and a monoazo pigment A liquid containing three different colored pigments, a discharge step of discharging the ink composition A1, the ink composition A2, the ink composition A3, and the ink composition B onto the substrate, and the ink discharged onto the substrate A heating step of heating the composition A1, the ink composition A2, the ink composition A3, and the ink composition B. Absorbance _{ABS A1} of Narubutsu A1, absorbance _{ABS A2} of the ink composition A2, the absorbance _{ABS A3} of the ink composition A3, and the absorbance ABS _B of the ink composition B, the following equation (5), equation (6) and ( 7) and the concentration M _{A1 of} the high boiling point solvent contained in the ink composition _A1 , the concentration M _{A2 of} the high boiling point solvent contained in the ink composition _A2 , and the concentration M of the high boiling point solvent contained in the ink composition A3. _A3, and the concentration _{M B} of the high-boiling solvent contained in the ink composition B, the following equation (8), it is preferable to satisfy equation (9) and (10).

ABS _A1 <ABS _B type (5)
ABS _A2 <ABS type _B (6)
ABS _A3 <ABS type _B (7)
M _A1 <M _B (8)
M _A2 <M _B (9)
M _A3 <M _B (10)

In the formulas (5), (6), and (7), ABS _A1 , ABS _A2 , ABS _A3 , and ABS _B are the ink composition A1, the ink composition A2, the ink composition A3, and the ink composition. The average value of the absorbance of B at a wavelength of 800 nm to 1400 nm is represented.
In the formula (8), the formula (9), and the formula (10), M _A1 , M _A2 , M _A3 , or M _B is the ink composition A1, the ink composition A2, the ink composition A3, or the ink composition B. Represents the concentration of the high-boiling solvent contained in the ink on the basis of mass relative to the total mass of each ink composition.
The absorbance at a wavelength of 800 nm to 1400 nm can be measured by the method described above.

The absorbance ABS _A1 of the ink composition _A1 and the absorbance ABS _{B of} the ink composition _B , the absorbance ABS _A2 of the ink composition _A2 , the absorbance ABS _{B of} the ink composition _B , and the absorbance ABS _A3 of the ink composition _A3 and the ink composition B That the absorbance ABS _B of the ink composition satisfies the formulas (5), (6), and (7) (that is, the ink composition A has a smaller absorbance than the ink composition B). When the same amount of infrared light (light having a wavelength of 800 nm to 1400 nm) is incident on the ink composition A2, the ink composition A3, and the ink composition B, the ink composition A1, the ink composition A2, and the ink composition A3 This indicates that the temperature of the composition is less likely to increase, and the ink composition B is more likely to increase the temperature of the composition.

When M _A1 , M _A2 , M _A3, or M _B satisfies Formula (8), Formula (9), and Formula (10), the ink composition A1, the ink composition A2, the ink composition A3, and the ink composition When the product B is heated, the ink composition B tends to have a lower zeta potential than the ink composition A1, the ink composition A2, and the ink composition A3, and the microcapsules tend to aggregate. Become. As a result, since the microcapsules can be aggregated before the destruction of the microcapsules in the ink composition B, color bleeding can be suppressed.

  Each component contained in the ink composition A1, the ink composition A2, the ink composition A3, and the ink composition B is the same as the ink composition A and the ink composition B described above, and the preferred embodiments are also the same. .

  Hereinafter, the embodiment of the present disclosure will be specifically described by way of examples. However, the embodiment of the present disclosure is not limited to the following examples as long as the gist of the present disclosure is not exceeded. Unless otherwise specified, “part” is based on mass.

[Preparation of microcapsule dispersion]
-Preparation of oil phase components-
Takenate D-120N (trifunctional or higher isocyanate compound, solid content 75% by weight, Mitsui Chemicals, Inc.) 4.58 g, Takenate D-116N (isocyanate compound having ethylene oxide group as hydrophilic group, ethyl acetate 50% by weight solution, Mitsui Chemicals, Inc.) 6.9 g, isocyanate compound having the following carboxy group (isocyanate compound having a carboxy group as a hydrophilic group, solid content 35 mass%) 5.14 g, SR399E (dipentaerythritol pentaacrylate, pentafunctional 3.5 g of polymerizable compound, SARTOMER), SR833S (tricyclodecane dimethanol diacrylate, bifunctional polymerizable compound, SARTOMER) 3.5 g, IRGACURE (registered trademark) 819 (photopolymerization initiator, BASF, Bisua Le phosphine oxide) 0.48 g, were dissolved in ethyl acetate 20g, to obtain an oil phase component.

--Synthesis of isocyanate compound having carboxy group--
To a three-necked flask, 45 g of 2,2-bis (hydroxymethyl) propionic acid (DMPA), 223.72 g of isophorone diisocyanate (IPDI), and 499.05 g of ethyl acetate (AcOEt) were added and heated to 50 ° C. Then, 0.7677 g of 600 was added and reacted for 3 hours to obtain an isocyanate compound having a carboxy group (an isocyanate compound having a hydrophilic group).

-Aqueous phase component-
8.08 g of a 1% by mass aqueous sodium hydroxide solution was dissolved in 35 g of distilled water to obtain an aqueous phase component.
The oil phase component and the aqueous phase component were mixed, and the obtained mixture was emulsified and dispersed at 12000 rpm for 12 minutes using a homogenizer to obtain an emulsion.

The obtained emulsion was stirred at 400 rpm and 45 ° C., and distilled water and ethyl acetate were distilled off. Stirring was further continued for 12 to 30 hours, and the solid content was adjusted to 25% by mass with water to obtain a microcapsule dispersion (hereinafter also referred to as “MC dispersion”).
The microcapsule includes a shell having a three-dimensional cross-linking structure including a hydrophilic group and at least one bond selected from a urethane bond and a urea bond, a bifunctional polymerizable compound, a pentafunctional polymerizable compound, and photopolymerization. And a core containing an initiator.
Here, the content of the photopolymerization initiator encapsulated in the microcapsule is 6.9% by mass with respect to the total content of the polymerizable compound encapsulated in the microcapsule.

<Confirmation that MC dispersion contains microcapsules>
It was confirmed by the following method that the MC dispersion obtained above contained microcapsules. In addition, the following operation was performed on the conditions of the liquid temperature of 25 degreeC.
A sample was taken from the MC dispersion obtained above. To the collected sample, 100 mass times tetrahydrofuran (THF) of the total solid content (microcapsules in this example) in this sample was added and mixed to prepare a diluted solution of MC dispersion. The obtained diluted solution was centrifuged (80000 rpm, 40 minutes). After centrifugation, the presence or absence of a residue is visually confirmed. If the residue is confirmed, water is added to this residue and stirred for 1 hour using a stirrer to re-disperse the residue with water. I got a thing. About the obtained redispersion, the particle size distribution was measured by the light-scattering method using the wet particle size distribution measuring apparatus (LA-960, Horiba, Ltd. make). When the particle size distribution was confirmed by the above operation, the MC dispersion was judged to contain microcapsules.

<Volume average dispersed particle diameter of microcapsules>
It was 0.15 micrometer when the volume average dispersed particle diameter of the microcapsule obtained above was measured by the light scattering method.
Here, a wet particle size distribution measuring apparatus LA-960 (manufactured by Horiba, Ltd.) was used for measurement of the volume average particle diameter by the light scattering method.

<Confirmation that the core contains a photopolymerization initiator>
About the MC dispersion obtained above, the inclusion rate (mass%) of a photoinitiator was measured, and it was confirmed whether the photoinitiator was contained in the core of the microcapsule. Details are shown below. In addition, the following operation was performed on the conditions of the liquid temperature of 25 degreeC.
Two samples (hereinafter referred to as “Sample 1A” and “Sample 2A”) having the same mass were collected from the MC dispersion.
To sample 1A, 100 mass times tetrahydrofuran (THF) with respect to the total solid content in sample 1A was added and mixed to prepare a diluted solution. The obtained diluted solution was centrifuged at 80,000 rpm for 40 minutes. The supernatant liquid produced by centrifugation (hereinafter referred to as “supernatant liquid 1A”) was collected. The mass of the photopolymerization initiator contained in the collected supernatant 1A was measured by a liquid chromatography apparatus “Waters 2695” manufactured by Waters. The mass of the obtained photopolymerization initiator was defined as “total amount of photopolymerization initiator”.
Further, the sample 2A was subjected to centrifugation under the same conditions as the centrifugation performed for the diluent. The supernatant liquid generated by centrifugation (hereinafter referred to as “supernatant liquid 2A”) was collected. The mass of the photopolymerization initiator contained in the collected supernatant 2A was measured by the liquid chromatography apparatus. The mass of the obtained photopolymerization initiator was defined as “free amount of photopolymerization initiator”.
Based on the “total amount of photopolymerization initiator” and the “free amount of photopolymerization initiator”, the encapsulation rate (% by mass) of the photopolymerization initiator was determined according to the following formula.

  Inclusion rate of photopolymerization initiator (mass%) = ((total amount of photopolymerization initiator−free amount of photopolymerization initiator) / total amount of photopolymerization initiator) × 100

  As a result, it was confirmed that the microcapsule had an encapsulation rate of 99% by mass or more and contained a photopolymerization initiator in the core.

<Confirmation that the core contains a polymerizable compound>
About MC dispersion obtained above, the inclusion rate (mass%) of the polymeric compound was measured, and it was confirmed whether the polymeric compound was contained in the core of the microcapsule.
The presence or absence of the polymerizable compound was confirmed by the same method as the confirmation of the inclusion of the photopolymerization initiator.
As a result, it was confirmed that the microcapsule had an encapsulation rate of 99% by mass or more and contained a polymerizable compound in the core. In addition, the inclusion rate of the polymeric compound here is the value calculated | required by the total amount of the polymeric compound of bifunctional or less and the polymeric compound of trifunctional or more.

[Preparation of ink composition]
Using the MC dispersion prepared above, the black ink (K1 to K8) in Table 2 below, the magenta ink (M1 to M3), the cyan ink (C1 to C5) and the yellow ink (Y1 to Y3) in Table 3 below. ) To prepare ink compositions of each color.
Each color ink composition was mixed with each component, stirred for 1 hour with a stirrer, and filtered with a filter having a pore size of 1.5 μm (PVDF 5 μm filter, Millex (registered trademark) -SV, diameter 25 mm, manufactured by Millipore). Thus, an ink composition was prepared.
The absorbance ABS (800 nm to 1400 nm) of each color ink composition was measured by adding a diluted solution obtained by diluting the ink composition to 1000 mass times with ultrapure water in a quartz cell having an optical path length of 0.2 mm, and using ultrapure water as a control cell. And measured. The measurement was performed using a spectrophotometer V-7200 (manufactured by JASCO Corporation) under the following conditions. And the average value of the light absorbency ABS of each ink composition was computed by averaging the measured light absorbency of 800 nm-1400 nm using following numerical formula (A).
Tables 2 and 3 below show the average absorbance ABS of the ink compositions of the respective colors.
-Condition-
Measurement wavelength: 800 nm to 1400 nm
Measurement interval: every 1 nm

Details of the components in Tables 2 and 3 are as follows.
Black pigment dispersion: Projet Black APD1000 (trade name), manufactured by FUJIFILM Imaging Colorants, carbon black concentration of 14% by mass
-Yellow pigment dispersion: Projet Yellow APD1000 (trade name), manufactured by FUJIFILM Imaging Colorants, Pigment Yellow 74, concentration of monoazo pigment: 16% by mass
-Magenta pigment dispersion: Projet Magenta APD1000 (trade name), manufactured by FUJIFILM Imaging Colorants, Inc., concentration of quinacridone pigment 14% by mass
Cyan pigment dispersion: Projet Cyan APD1000 (trade name), manufactured by FUJIFILM Imaging Colorants, a concentration of 14% by mass of copper phthalocyanine pigment
・ MC dispersion: Concentration of microcapsule 25% by mass
・ Capstone FS-31 Fluorosurfactant, manufactured by DuPont, solid content 25% by mass

[Examples 1-21, Comparative Examples 1-3]
Using the ink compositions of the respective colors prepared above, image recording was performed by the ink jet recording method of Examples or Comparative Examples and evaluated. Details are as follows.
<Image recording and evaluation>
As shown in Tables 4 to 7 below, ink compositions A (shown as Liquid A in Tables 4 to 7) and Ink Composition B (shown as Liquid B in Tables 4 to 6) as shown in Tables 4 to 7 below. As an ink set, image recording was performed using each ink set, and the following evaluation was performed. The results are shown in Tables 4 to 7 below.

(Preparation of sample for evaluation)
Two ink jet heads connected to storage tanks filled with ink composition A and ink composition B of the ink sets of combinations shown in Tables 4 to 7 below, and an infrared irradiation device (peak in the region of wavelengths 800 nm to 1400 nm) Using an inkjet printer having a wavelength, manufactured by Adphos, Adphos NIR), and an ultraviolet exposure device (peak wavelength: 254 nm, manufactured by Heraeus, Long Life Amalgam Lamp), a polyvinyl chloride base material (produced by Avery Dennison, Ink composition A and ink composition B were ejected onto AVERY 400 GLOSS WHITE PERMANENT (trade name).
The ejection conditions were set so that the resolution of the recorded image was 1200 dpi × 900 dpi (dot per inch), and ejection was performed from two heads to record the image shown in FIG. The image shown in FIG. 1 has a fine line portion 1 for color bleed evaluation (set width: 1 mm, length: 10 cm) and a solid image portion 2 for wear resistance evaluation. In FIG. 1, A is a portion recorded with the ink composition A, and B is a portion recorded with the ink composition B.
0.1 seconds after the ink landed on the base material, the image recorded portion was heated by the infrared irradiation device under the conditions of the base material surface temperature of 70 ° C. for 0.2 second, and after the heating, 30 seconds. After 2 seconds, the ultraviolet ray exposure device was used to irradiate light on the image-recorded portion, and each sample for evaluation was produced so that the exposure amount of the light-irradiated portion was 300 mJ / cm ² .

(1. Image quality)
In the evaluation sample prepared by performing light irradiation at 300 mJ / cm ² described above, the width of the fine line portion 1 of the formed image was measured, and the image quality was evaluated according to the following evaluation criteria. In addition, evaluation of the width | variety of the thin wire | line part 1 evaluated by the one with the big shift | offset | difference with setting value 1mm among the thin wire | line parts 1 formed with the ink composition A and the ink composition B. Here, the width of the thin line portion 1 is an average value measured at arbitrary three points of the thin line portion 1.
In addition, it is inferior to a color bleed, so that the width | variety of the thin wire | line part 1 is thick with respect to the setting value 1mm, and it is inferior to graininess, so that it is thin with respect to the setting value 1mm.
-Evaluation criteria-
A: The widths of the thin line portions of the ink composition A and the ink composition B are both 1 mm.
B: The widths of the thin line portions of the ink composition A and the ink composition B are 0.9 mm or more and 1.1 mm or less.
C: The width of the thin line portion of the ink composition A and the ink composition B is less than 0.9 mm or more than 1.1 mm.

(2. Wear resistance)
In the sample for evaluation produced by irradiating light at 300 mJ / cm ² above, the solid image portion of the formed image is made of cotton wetted with ultrapure water, and the solid image portion ink composition is used. The Gakushin test was conducted under the following conditions so as to straddle the boundary portion between the portion recorded with A and the portion recorded with the ink composition B, and the wear resistance was evaluated according to the following evaluation criteria. For the evaluation, the result of the inferior evaluation result of the portion recorded with the ink composition A and the portion recorded with the ink composition B was adopted. In the following evaluation criteria, evaluation results of 3, 4, and 5 were determined to be acceptable.
-Condition-
Equipment: AB-301 Gakushin type friction fastness tester, Tester Sangyo Co., Ltd.
Test load: 200g
Number of reciprocations: 3, 5, 10, 15, 20 -Evaluation criteria-
5: The image was not peeled off from the substrate even after 20 reciprocations.
4: The image peeled off from the substrate after 15 reciprocations.
3: The image peeled off from the substrate after 10 reciprocations.
2: The image peeled off from the substrate after 5 reciprocations.
1: The image peeled off from the substrate after 3 reciprocations.

(3. Dischargeability)
The ink sets shown in Tables 4 to 7 below are 1 m × 0.5 m size as shown in FIG. 2 using the same ink jet printer, the same discharge conditions, and the same base material as those used for the preparation of the above-described evaluation samples. A pattern in which the images of No. 1 were arranged with a certain margin was recorded on the substrate. Images were recorded by conveying the substrate in the vertical direction of FIG. 2 and scanning the head in the horizontal direction. The exposure amount was 300 mJ / cm ² .
The image shown in FIG. 2 is an image in which squares (1 cm × 1 cm) recorded with the ink composition A and the ink composition B are alternately arranged, and has a margin X.
The length of the margin X was adjusted so as to have a rest time (a time during which no ejection is performed) of 2 seconds, 3 seconds, 4 seconds, or 5 seconds.
The image after recording was visually observed, and the ejection property was evaluated according to the following evaluation criteria. In the following evaluation criteria, evaluation results of 3, 4, and 5 were determined to be acceptable.
-Evaluation criteria-
5: No missing image was observed even when the margin X was equivalent to 5 seconds.
4: No missing image was observed until the margin X was equivalent to 4 seconds.
3: No missing image was observed until the margin X was equivalent to 3 seconds.
2: The image quality deteriorated when the margin X was 3 seconds.
1: The image quality deteriorated when the margin X was equivalent to 2 seconds.

(4. Color development)
A solid image of each ink composition having a size of 2 cm × 2 cm using the ink sets shown in Tables 4 to 7 below using the same ink jet printer, the same discharge conditions, and the same base material as those used in the preparation of the evaluation sample. Was recorded on the substrate. The exposure amount was 300 mJ / cm ² .
The reflection density (saturation) of the image of each ink composition was measured with a colorimeter (SpectroEye, Xrite).
The reflection density (saturation) of the image of the ink composition A obtained by measurement and the reflection density (saturation) of the image of the ink composition B were evaluated for color development according to the following evaluation criteria. In addition, the lower evaluation score was adopted as the evaluation result. In addition, in the following evaluation criteria, evaluation results of 3, 4, and 5 were judged to be acceptable.
-Evaluation criteria-
5: The saturation of cyan is 60 or more, the saturation of magenta is 75 or more, the saturation of yellow is 90 or more, or the density of black is 2.0 or more.
4: Cyan saturation is less than 60 and 58 or more, magenta saturation is less than 75 and 72.5 or more, yellow saturation is less than 90 and 85 or more, or black density is less than 2.0 and 1.9 or more.
3: Cyan saturation is less than 58 and 56 or more, magenta saturation is less than 72.5 and 70 or more, yellow saturation is less than 85 and 80 or more, or black density is less than 1.9 and 1.8 or more.
2: Cyan saturation is less than 56, 54 or more, magenta saturation is less than 70, 67.5 or more, yellow saturation is less than 80, 75 or more, or black density is less than 1.8, 1.7 or more.
1: Cyan saturation is less than 54, magenta saturation is less than 67.5, yellow saturation is less than 75, or black density is less than 1.7.

  From Tables 4 to 7, it can be seen that the evaluation results of color bleeding, graininess, abrasion resistance, dischargeability, and color development are excellent in the examples. From this, it can be said that the example is an ink jet recording method in which color bleeding is suppressed.

<Image recording and evaluation in four colors>
Four ink jet heads connected to storage tanks filled with ink compositions (A1, A2, A3, and B) of the respective colors in the combinations described in Table 8 below, and an infrared irradiation device (wavelength 800 nm to Using an inkjet printer having a peak wavelength in the region of 1400 nm and having an ultraviolet exposure device (peak wavelength: 254 nm, manufactured by Heraeus, Long Life Amalgam Lamp), a polyvinyl chloride substrate (Avery) The ink composition of each color was ejected onto AVERY 400 GLOSS WHITE PERMANENT (trade name) manufactured by Denison.
The ejection conditions were set such that the resolution of the image after recording was 1200 dpi × 900 dpi (dot per inch), and ejection was performed from four heads to record the image shown in FIG. The image shown in FIG. 3 has a fine line portion 11 (set width: 1 mm, length: 10 cm) for color bleed evaluation and a solid image portion 12 for wear resistance evaluation.
0.1 seconds after image recording, the image recorded portion was heated by an infrared irradiation device under the conditions of 70 ° C. and 0.2 second, and further, the ultraviolet image exposure device was used to heat the image recorded portion. Then, each of the samples for evaluation was prepared so that the exposure amount of the irradiated portion was 300 mJ / cm ² .

For the four-color evaluation sample, the above 1. Color bleed, 2. 2. Abrasion resistance; 3. discharge performance, and Color development was evaluated. The evaluation results are shown in Table 7 below.
3. The ejection performance was carried out by recording the image shown in FIG. 4 on the substrate. The image shown in FIG. 4 is an image in which squares recorded with cyan (C), magenta (M), yellow (Y), and black (K) ink compositions are arranged in order, and has a margin X. The margin X is as described above.

  From Table 8, it can be seen that the color bleed, graininess, abrasion resistance, dischargeability, and color development are excellent. From this, it can be said that this is an ink jet recording method in which color bleeding is suppressed.

The disclosure of Japanese Patent Application No. 2006-087064 filed on April 25, 2016 is incorporated herein by reference in its entirety.
All documents, patent applications, and technical standards mentioned in this specification are to the same extent as if each individual document, patent application, and technical standard were specifically and individually described to be incorporated by reference, Incorporated herein by reference.

Claims (13)

Ink composition A including at least a microcapsule encapsulating a polymerizable compound, a high boiling point solvent, water, and a colorant, and an ink including a microcapsule encapsulating at least a polymerizable compound, a high boiling point solvent, water, and carbon black A discharge step of discharging the composition B onto a substrate;
A heating step of heating the ink composition A and the ink composition B discharged to the substrate,
Absorbance ABS _B absorbance ABS _A and the ink composition B of the ink composition A is satisfies the following formula (1), and the concentration M _A and the ink of the high boiling point solvent contained in the ink composition A the high boiling solvent the concentration M _B-jet recording method which satisfies the following formula (2) contained in the composition B.
ABS _A <ABS _B type (1)
M _A <M _B (2)
In formula (1), ABS _A and ABS _B represent the average values of the absorbances of the ink composition A and the ink composition B at wavelengths of 800 nm to 1400 nm, respectively.
In the formula (2), M _A or M _B represents a mass-based concentration of the high boiling point solvent contained in the ink composition A or the ink composition B with respect to the total mass of each ink composition.   The inkjet recording method according to claim 1, wherein in the heating step, the ink composition A and the ink composition B are heated by irradiation with infrared rays. The ABS _A, the ABS _B, wherein _{M A,} and the _{M B-jet} recording method according to claim 1 or claim 2 satisfies the following equation (3).
_{{1 + 0.01 × (ABS B} / ABS A)} × M A <M B <{1 + 0.04 × (ABS B / ABS A)} × M A formula (3) The ABS _A, the ABS _B, wherein _{M A,} and the _{M B-jet} recording method according to any one of claims 1 to 3 satisfying the following formula (4).
_{{1 + 0.015 × (ABS B} / ABS A)} × M A <M B <{1 + 0.03 × (ABS B / ABS A)} × M A (4) The M _A is 5% by mass to 12% by mass with respect to the total mass of the ink composition A, and the M _B is 7% by mass to 15% by mass with respect to the total mass of the ink composition B. The inkjet recording method according to any one of claims 1 to 4.   6. The ink jet recording method according to claim 1, wherein in the heating step, the ink composition A and the ink composition B are heated under the same conditions.   The ink composition A contains 4.0% by mass to 6.0% by mass of a quinacridone pigment as the colorant with respect to the total mass of the ink composition A, and the ink composition B is an ink composition B. The inkjet recording method according to any one of claims 1 to 6, comprising 1.5% by mass to 2.5% by mass of carbon black based on the total mass of the ink.   The ink composition A contains 1.7% by mass to 3.1% by mass of a copper phthalocyanine pigment as the colorant with respect to the total mass of the ink composition A, and the ink composition B is an ink composition. The ink jet recording method according to any one of claims 1 to 6, comprising 1.5% by mass to 2.5% by mass of carbon black with respect to the total mass of B.   The ink composition A contains 3.0% by mass to 4.4% by mass of a monoazo pigment as the colorant with respect to the total mass of the ink composition A, and the ink composition B is an ink composition B. The inkjet recording method according to any one of claims 1 to 6, comprising 1.5% by mass to 2.5% by mass of carbon black based on the total mass of the ink.   The high boiling point solvent contained in the ink composition A and the ink composition B is a water-soluble solvent having a boiling point of 180 ° C or higher and 280 ° C or lower, respectively. Inkjet recording method.   11. The ink jet recording method according to claim 1, wherein each of the microcapsules contained in the ink composition A and the ink composition B further contains a photopolymerization initiator.   The ink jet recording method according to claim 1, further comprising an irradiation step of irradiating light to the ink composition A and the ink composition B heated by the heating step. The ink composition A includes at least a microcapsule encapsulating a polymerizable compound, a high boiling point solvent, water, and an ink composition A1 containing a copper phthalocyanine pigment, at least a microcapsule encapsulating the polymerizable compound, a high boiling point solvent, water And an ink composition A2 containing a quinacridone pigment, and an ink composition A3 containing a microcapsule containing at least a polymerizable compound, a high boiling point solvent, water, and a monoazo pigment,
In the ejection step, the ink composition A1, the ink composition A2, the ink composition A3, and the ink composition B are ejected onto a substrate,
The heating step heats the ink composition A1, the ink composition A2, the ink composition A3, and the ink composition B discharged onto the base material, and
The absorbance ABS _{A1 of} the ink composition _A1 , the absorbance ABS _{A2 of} the ink composition _A2 , the absorbance ABS _{A3 of} the ink composition _A3 , and the absorbance ABS _B of the ink composition _B are expressed by the following formulas (5) and ( 6) and the formula (7) are satisfied, and the high boiling point solvent concentration M _A1 contained in the ink composition _A1 , the high boiling point solvent concentration M _A2 contained in the ink composition _A2 , and the ink composition A3 concentration M _B of the high-boiling solvent contained in the high boiling solvent the concentration M _A3, and the ink composition B which contains the following formula (8), satisfies the equation (9) and (10), according to claim The inkjet recording method according to any one of claims 1 to 12.
ABS _A1 <ABS _B type (5)
ABS _A2 <ABS type _B (6)
ABS _A3 <ABS type _B (7)
M _A1 <M _B (8)
M _A2 <M _B (9)
M _A3 <M _B (10)
In the formulas (5), (6), and (7), ABS _A1 , ABS _A2 , ABS _A3 , and ABS _B are the ink composition A1, the ink composition A2, the ink composition A3, and the ink composition. The average value of the absorbance of each of B at wavelengths of 800 nm to 1400 nm is represented.
In the formula (8), the formula (9), and the formula (10), M _A1 , M _A2 , M _A3 , or M _B is the ink composition A1, the ink composition A2, the ink composition A3, or the ink composition B. Represents the concentration of the high boiling point solvent contained in the ink on the basis of the mass relative to the total mass of each ink composition.